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  1. Metal-on-metal total hip arthroplasty: the concerns.

    PubMed

    MacDonald, S J

    2004-12-01

    The metal-on-metal bearing couple is having a resurgence in clinical applications seen in total hip and hip resurfacing technologies. The most noteworthy advantage of a metal-on-metal implant is the improved wear characteristics seen in vitro on wear simulators and in vivo with retrieved implants. All bearings have disadvantages, and a metal-on-metal bearing is no exception. Concerns exist regarding the generation of metal ions seen in the blood and urine of patients with metal-on-metal implants. These elevated metal ions have theoretical, although not proven, risks related to carcinogenic and biologic concerns. Additionally, concerns exist regarding hypersensitivity, increased incidence of instability and increased costs. Specific patient selection issues arise with metal-on-metal implants. The current generation of implants has only early and mid-term results available, with no long-term series yet published. Therefore, although a metal-on-metal bearing may be considered a viable alternative to either polyethylene or ceramic implants, outstanding and unresolved issues continue to exist with this bearing, as they do with the alternatives. PMID:15577471

  2. Metal-on-Metal Total Hip Resurfacing Arthroplasty

    PubMed Central

    2006-01-01

    Executive Summary Objective The objective of this review was to assess the safety and effectiveness of metal on metal (MOM) hip resurfacing arthroplasty for young patients compared with that of total hip replacement (THR) in the same population. Clinical Need Total hip replacement has proved to be very effective for late middle-aged and elderly patients with severe degenerative diseases of the hips. As indications for THR began to include younger patients and those with a more active life style, the longevity of the implant became a concern. Evidence suggests that these patients experience relatively higher rates of early implant failure and the need for revision. The Swedish hip registry, for example, has demonstrated a survival rate in excess of 80% at 20 years for those aged over 65 years, whereas this figure was 33% by 16 years in those aged under 55 years. Hip resurfacing arthroplasty is a bone-conserving alternative to THR that restores normal joint biomechanics and load transfer. The technique has been used around the world for more than 10 years, specifically in the United Kingdom and other European countries. The Technology Metal-on-metal hip resurfacing arthroplasty is an alternative procedure to conventional THR in younger patients. Hip resurfacing arthroplasty is less invasive than THR and addresses the problem of preserving femoral bone stock at the initial operation. This means that future hip revisions are possible with THR if the initial MOM arthroplasty becomes less effective with time in these younger patients. The procedure involves the removal and replacement of the surface of the femoral head with a hollow metal hemisphere, which fits into a metal acetabular cup. Hip resurfacing arthroplasty is a technically more demanding procedure than is conventional THR. In hip resurfacing, the femoral head is retained, which makes it much more difficult to access the acetabular cup. However, hip resurfacing arthroplasty has several advantages over a

  3. The Clinical Performance of Metal-on-Metal as an Articulation Surface in Total Hip Replacement

    PubMed Central

    Long, William T

    2005-01-01

    The metal-on-metal articulations in total hip arthroplasty (THA) were widely used between 1960 and 1975. The McKee-Farrar and other first-generation prostheses failed at a high rate because impingement caused early component loosening. The problem of early component loosening was corrected by improved component design and better manufacturing quality. Second-generation metal-on-metal total hip replacements have experienced short and medium-term success as assessed by Harris Hip Scores and patient selfassessment. The combined annual linear wear of the metal-on-metal femoral head and acetabular insert is less than 10 mm and osteolysis has only rarely been observed in association with well-fixed metal-on-metal total hip replacements. Hypersensitivity is not a common cause of loosening with second-generation hip replacements and remains to be proven as a definitive diagnosis in unusual cases of unexplained pain. More than 40 years of use has demonstrated no increase in the incidence of renal failure or cancer in patients with metal-on-metal total hip replacements. The scientific evidence of the results using the metal-on-metal articulations would recommend its continued use in any patient who does not have compromised renal function. PMID:16089065

  4. Metallic debris from metal-on-metal total hip arthroplasty regulates periprosthetic tissues

    PubMed Central

    Lohmann, Christoph H; Singh, Gurpal; Willert, Hans-Georg; Buchhorn, Gottfried H

    2014-01-01

    The era of metal-on-metal (MoM) total hip arthroplasty has left the orthopaedic community with valuable insights and lessons on periprosthetic tissue reactions to metallic debris. Various terms have been used to describe the tissue reactions. Sometimes the nomenclature can be confusing. We present a review of the concepts introduced by Willert and Semlitsch in 1977, along with further developments made in the understanding of periprosthetic tissue reactions to metallic debris. We propose that periprosthetic tissue reactions be thought of as (1) gross (metallosis, necrosis, cyst formation and pseudotumour); (2) histological (macrophage-dominated, lymphocyte-dominated or mixed); and (3) molecular (expression of inflammatory mediators and cytokines such as interleukin-6 and tumor necrosis factor-alpha). Taper corrosion and modularity are discussed, along with future research directions to elucidate the antigen-presenting pathways and material-specific biomarkers which may allow early detection and intervention in a patient with adverse periprosthetic tissue reactions to metal wear debris. PMID:25405095

  5. Complications Related to Metal-on-Metal Articulation in Trapeziometacarpal Joint Total Joint Arthroplasty

    PubMed Central

    Frølich, Christina; Hansen, Torben Bæk

    2015-01-01

    Adverse reactions to metal-on-metal (MoM) prostheses are well known from total hip joint resurfacing arthroplasty with elevated serum chrome or cobalt, pain and pseudo tumor formation. It may, however, also be seen after total joint replacement of the trapeziometacarpal joint using MoM articulation, and we present two cases of failure of MoM prostheses due to elevated metal-serum levels in one case and pseudo tumor formation in another case. Furthermore, we suggest a diagnostic algorithm for joint pain after MoM trapeziometacarpal joint replacement based on published experiences from MoM hip prostheses and adverse reactions to metal. PMID:26020592

  6. Early surveillance of ceramic-on-metal total hip arthroplasty.

    PubMed

    Hill, J C; Diamond, O J; O'Brien, S; Boldt, J G; Stevenson, M; Beverland, D E

    2015-03-01

    Ceramic-on-metal (CoM) is a relatively new bearing combination for total hip arthroplasty (THA) with few reported outcomes. A total of 287 CoM THAs were carried out in 271 patients (mean age 55.6 years (20 to 77), 150 THAs in female patients, 137 in male) under the care of a single surgeon between October 2007 and October 2009. With the issues surrounding metal-on-metal bearings the decision was taken to review these patients between March and November 2011, at a mean follow-up of 34 months (23 to 45) and to record pain, outcome scores, radiological analysis and blood ion levels. The mean Oxford Hip Score was 19.2 (12 to 53), 254 patients with 268 hips (95%) had mild/very mild/no pain, the mean angle of inclination of the acetabular component was 44.8(o) (28(o) to 63(o)), 82 stems (29%) had evidence of radiolucent lines of > 1 mm in at least one Gruen zone and the median levels of cobalt and chromium ions in the blood were 0.83 μg/L (0.24 μg/L to 27.56 μg/L) and 0.78 μg/L (0.21 μg/L to 8.84 μg/L), respectively. The five-year survival rate is 96.9% (95% confidence interval 94.7% to 99%). Due to the presence of radiolucent lines and the higher than expected levels of metal ions in the blood, we would not recommend the use of CoM THA without further long-term follow-up. We plan to monitor all these patients regularly. PMID:25737511

  7. Does bearing size influence metal ion levels in large-head metal-on-metal total hip arthroplasty? A comparison of three total hip systems

    PubMed Central

    2014-01-01

    Background The purpose of the study was twofold: first, to determine whether there is a statistically significant difference in the metal ion levels among three different large-head metal-on-metal (MOM) total hip systems. The second objective was to assess whether position of the implanted prostheses, patient demographics or factors such as activity levels influence overall blood metal ion levels and whether there is a difference in the functional outcomes between the systems. Methods In a cross-sectional cohort study, three different metal-on-metal total hip systems were assessed: two monoblock heads, the Durom socket (Zimmer, Warsaw, IN, USA) and the Birmingham socket (Smith and Nephew, Memphis, TN, USA), and one modular metal-on-metal total hip system (Pinnacle, Depuy Orthopedics, Warsaw, IN, USA). Fifty-four patients were recruited, with a mean age of 59.7 years and a mean follow-up time of 41 months (12 to 60). Patients were evaluated clinically, radiologically and biochemically. Statistical analysis was performed on all collected data to assess any differences between the three groups in terms of overall blood metal ion levels and also to identify whether there was any other factor within the group demographics and outcomes that could influence the mean levels of Co and Cr. Results Although the functional outcome scores were similar in all three groups, the blood metal ion levels in the larger monoblock large heads (Durom, Birmingham sockets) were significantly raised compared with those of the Pinnacle group. In addition, the metal ion levels were not found to have a statistically significant relationship to the anteversion or abduction angles as measured on the radiographs. Conclusions When considering a MOM THR, the use of a monoblock large-head system leads to higher elevations in whole blood metal ions and offers no advantage over a smaller head modular system. PMID:24472283

  8. Short-term results with the Zweymueller-SL metal-on-metal total hip arthroplasty.

    PubMed

    Korovessis, Panagiotis; Petsinis, Georgios; Repanti, Maria; Papazisis, Zisis; Iliopoulos, Panagiotis; Soucacos, Panagiotis N

    2002-01-01

    In a prospective study we followed 266 consecutive patients who received 350 Zweymueller-SL uncemented total hip replacements with metal-on-metal articulation for osteoarthritis. Mean follow-up was 52 (range 37-92) months. Patient age at the time of surgery was 55±9 (25-70) years. Pre-operative Harris score of 45±19 was increased post-operatively to 96±4. Pre-operative invalidity was significantly improved post-operatively (P<0.001), and 97% of the patients were either satisfied or very satisfied with the results. There was no aseptic loosening of either component. Revision was made in six hips (1.8%) because of either septic loosening (five, 1.5%) or technical error (one, 0.3%). At revision, surgical microscopic evidence for metalosis (Mirra grades 1 and 2) was shown in all revised hips. The reasons for early loosening were unrelated to the metal-on-metal bearing but rather were the result of either low-grade deep infection or inadequate surgical technique. Survival rate for Zweymueller screw socket and stem 7.6 years after implantation was 99.4% and 96.8% respectively. There was no evidence that metal-on-metal articulation gives rise to new problems or complications. PMID:24570158

  9. Metal-on-metal total hip arthroplasty: is there still a role in 2016?

    PubMed

    Silverman, Edward J; Ashley, Blair; Sheth, Neil P

    2016-03-01

    The use of metal-on-metal (MoM) bearings in total hip arthroplasty (THA) was popularized due to its enhanced wear profile and the ability to use large femoral heads to reduce post-operative instability. However, enthusiasm for the bearing declined following serious complications encountered at the primary articulation. This review discusses the development of MoM and the subsequent unexpected downstream challenges, most notably elevated serum metal ion levels, aseptic lymphocyte-dominated vasculitis-associated lesions (ALVAL), pseudotumor formation, and subsequent soft tissue and bone destruction. Both patient centered risk factors as well as component design led to high early failure rates resulting in product recalls and an overall decline in the use of MoM. In 2016, there is not a role for large-head MoM bearing in THA. Alternatively, the bearing has shown promise in hip resurfacing procedures for carefully selected patients. PMID:26791173

  10. Understanding the differences between the wear of metal-on-metal and ceramic-on-metal total hip replacements.

    PubMed

    Figueiredo-Pina, C G; Yan, Y; Neville, A; Fisher, J

    2008-04-01

    Hip simulator studies have been carried out extensively to understand and test artificial hip implants in vitro as an efficient alternative to obtaining long-term results in vivo. Recent studies have shown that a ceramic-on-metal material combination lowers the wear by up to 100 times in comparison with a typical metal-on-metal design. The reason for this reduction remains unclear and for this reason this study has undertaken simple tribometer tests to understand the fundamental material loss mechanisms in two material combinations: metal-on-metal and ceramic-on-ceramic. A simple-configuration reciprocating pin-on-plate wear study was performed under open-circuit potential (OCP) and with applied cathodic protection (CP) in a serum solution using two tribological couples: firstly, cobalt-chromium (Co-Cr) pins against Co-Cr plates; secondly, Co-Cr pins against alumina (Al2O3) plates. The pin and plate surfaces prior to and after testing were examined by profilometry and scanning electron microscopy. The results showed a marked reduction in wear when CP was applied, indicating that total material degradation under the OCP condition was attributed to corrosion processes. The substitution of the Co-Cr pin with an Al2O3 plate also resulted in a dramatic reduction in wear, probably due to the reduction in the corrosion-wear interactions between the tribological pair. PMID:18491698

  11. Friction in metal-on-metal total disc arthroplasty: effect of ball radius.

    PubMed

    Moghadas, Parshia; Mahomed, Aziza; Hukins, David W L; Shepherd, Duncan E T

    2012-02-01

    Total disc arthroplasty (TDA) can be used to replace a degenerated intervertebral disc in the spine. There are different designs of prosthetic discs, but one of the most common is a ball-and-socket combination. Contact between the bearing surfaces can result in high frictional torque, which can then result in wear and implant loosening. This study was designed to determine the effects of ball radius on friction. Generic models of metal-on-metal TDA were manufactured with ball radii of 10, 12, 14 and 16 mm, with a radial clearance of 0.015 mm. A simulator was used to test each sample in flexion-extension, lateral bending and axial rotation at frequencies of 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75 and 2 Hz under loads of 50, 600, 1200 and 2000 N, in new born calf serum. Frictional torque was measured and Stribeck curves were plotted to illustrate the lubrication regime in each case. It was observed that implants with a smaller ball radius showed lower friction and showed boundary and mixed lubrication regimes, whereas implants with larger ball radius showed boundary lubrication only. This study suggests designing metal-on-metal TDAs with ball radius of 10 or 12 mm, in order to reduce wear and implant loosening. PMID:22177670

  12. High Re-Operation Rates Using Conserve Metal-On-Metal Total Hip Articulations

    PubMed Central

    Mogensen, S.L.; Jakobsen, T.; Christoffersen, H.; Krarup, N.

    2016-01-01

    Introduction: Metal-on-metal hip articulations have been intensely debated after reports of adverse reactions and high failure rates. The aim of this study was to retrospectively evaluate the implant of a metal-on.metal total hip articulation (MOM THA) from a single manufacture in a two-center study. Materials and Methods: 108 CONSERVE® MOM THA were implanted in 92 patients between November 2005 and December 2010. Patients had at time of retrospective evaluation their journals reviewed for re-operations and adverse reactions. Results: 20 hips were re-operated (18.4%) at a mean follow up of 53 months. 4 pseudotumors were diagnosed at time of follow up but no substantiated link was made between adverse reactions and re-operations. Conclusion: The high re-operation rates found in this study raised concern about the usage of the MOM THA and subsequently lead to the termination of implantation of this MOM THA at the two orthopaedic departments. PMID:27099640

  13. No association between serum metal ions and implant fixation in large-head metal-on-metal total hip arthroplasty

    PubMed Central

    Søballe, Kjeld; Jakobsen, Stig Storgaard; Lorenzen, Nina Dyrberg; Mechlenburg, Inger; Stilling, Maiken

    2014-01-01

    Background The mechanism of failure of metal-on-metal (MoM) total hip arthroplasty (THA) has been related to a high rate of metal wear debris, which is partly generated from the head-trunnion interface. However, it is not known whether implant fixation is affected by metal wear debris. Patients and methods 49 cases of MoM THA in 41 patients (10 women) with a mean age of 52 (28–68) years were followed with stereoradiographs after surgery and at 1, 2, and 5 years to analyze implant migration by radiostereometric analysis (RSA). Patients also participated in a 5- to 7-year follow-up with measurement of serum metal ions, questionnaires (Oxford hip score (OHS) and Harris hip score (HHS)), and measurement of cup and stem positions and systemic bone mineral density. Results At 1–2 years, mean total translation (TT) was 0.04 mm (95% CI: –0.07 to 0.14; p = 0.5) for the stems; at 2–5 years, mean TT was 0.13 mm (95% CI: –0.25 to –0.01; p = 0.03), but within the precision limit of the method. For the cups, there was no statistically significant TT or total rotation (TR) at 1–2 and 2–5 years. At 2–5 years, we found 4 cups and 5 stems with TT migrations exceeding the precision limit of the method. There was an association between cup migration and total OHS < 40 (4 patients, 4 hips; p = 0.04), but there were no statistically significant associations between cup or stem migration and T-scores < –1 (n = 10), cup and stem positions, or elevated serum metal ion levels (> 7µg/L (4 patients, 6 hips)). Interpretation Most cups and stems were well-fixed at 1–5 years. However, at 2–5 years, 4 cups and 5 stems had TT migrations above the precision limits, but these patients had serum metal ion levels similar to those of patients without measurable migrations, and they were pain-free. Patients with serum metal ion levels > 7 µg/L had migrations similar to those in patients with serum metal ion levels < 7 µg/L. Metal wear debris does not appear to influence the

  14. Midterm results of 36 mm metal-on-metal total hip arthroplasty

    PubMed Central

    Akrawi, Hawar; Hossain, Fahad S; Niculescu, Stefan; Hashim, Zaid; Ng, Arron Biing; Shetty, Ajit

    2016-01-01

    Background: Despite the many perceived benefits of metal-on-metal (MoM) articulation in total hip arthroplasty (THA), there have been growing concerns about metallosis and adverse reaction to metal debris (ARMD). Analysis of size 36 mm MoM articulation THAs is presented. These patients were evaluated for patient characteristics, relationship between blood metal ions levels and the inclination as well as the version of acetabular component, cumulative survival probability at final followup and functional outcome at final followup. Materials and Methods: 288, size 36 mm MoM THAs implanted in 269 patients at our institution from 2004 to 2010 were included in this retrospective study. These patients were assessed clinically for hip symptoms, perioperative complications and causes of revision arthroplasty were analysed. Biochemically, blood cobalt and chromium metal ions level were recorded and measurements of acetabular inclination and version were examined. Radiological evaluation utilizing Metal Artefact Reduction Sequence (MARS) MRI was undertaken and implant cumulative survivorship was evaluated. Results: The mean followup was 5 years (range 2–7 years), mean age was 73 years and the mean Oxford hip score was 36.9 (range 5–48). Revision arthroplasty was executed in 20 (7.4%) patients, of which 15 patients underwent single-stage revision THA. The causes of revision arthroplasty were: ARMD changes in 6 (2.2%) patients, infection in 5 (1.9%) patients and aseptic loosening in 5 (1.9%) patients. Three (1.1%) patients had their hips revised for instability, 1 (0.3%) for raised blood metal ions levels. The implant cumulative survival rate, with revision for any reason, was 68.9% at 7 years. Conclusions: Although medium-sized MoM THA with a 36 mm head has a marginally better survivorship at midterm followup, compared to larger size head MoM articulating THA, our findings nonetheless are still worryingly poor in comparison to what has been quoted in the literature

  15. Perfusion MRI in hips with metal-on-metal and metal-on-polyethylene total hip arthroplasty

    PubMed Central

    Anwander, H.; Cron, G. O.; Rakhra, K.

    2016-01-01

    Objectives Hips with metal-on-metal total hip arthroplasty (MoM THA) have a high rate of adverse local tissue reactions (ALTR), often associated with hypersensitivity reactions. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) measures tissue perfusion with the parameter Ktrans (volume transfer constant of contrast agent). Our purpose was 1) to evaluate the feasibility of DCE-MRI in patients with THA and 2) to compare DCE-MRI in patients with MoM bearings with metal-on-polyethylene (MoP) bearings, hypothesising that the perfusion index Ktrans in hips with MoM THA is higher than in hips with MoP THA. Methods In this pilot study, 16 patients with primary THA were recruited (eight MoM, eight MoP). DCE-MRI of the hip was performed at 1.5 Tesla (T). For each patient, Ktrans was computed voxel-by-voxel in all tissue lateral to the bladder. The mean Ktrans for all voxels was then calculated. These values were compared with respect to implant type and gender, and further correlated with clinical parameters. Results There was no significant difference between the two bearing types with both genders combined. However, dividing patients by THA bearing and gender, women with MoM bearings had the highest Ktrans values, exceeding those of women with MoP bearings (0.067 min−1 versus 0.053 min−1; p-value < 0.05) and men with MoM bearings (0.067 min−1 versus 0.034 min−1; p-value < 0.001). Considering only the men, patients with MoM bearings had lower Ktrans than those with MoP bearings (0.034 min−1 versus 0.046 min−1; p < 0.05). Conclusion DCE-MRI is feasible to perform in tissues surrounding THA. Females with MoM THA show high Ktrans values in DCE-MRI, suggesting altered tissue perfusion kinematics which may reflect relatively greater inflammation. Cite this article: Dr P. E. Beaule. Perfusion MRI in hips with metal-on-metal and metal-on-polyethylene total hip arthroplasty: A pilot stud. Bone Joint Res 2016;5:73–79. DOI: 10

  16. Acute delayed infection: increased risk in failed metal on metal total hip arthroplasty.

    PubMed

    Prieto, Hernan A; Berbari, Elie F; Sierra, Rafael J

    2014-09-01

    Adverse local tissue reactions occurring in metal-on-metal total hip arthroplasty (MoM THA) could potentially lead to secondary failure modes such as dislocation or infection. The authors report a series of 124 patients treated with MoM hip arthroplasty between 2006 and 2010 with a minimum follow-up of 3 years. Eight hips presented with acute delayed or late periprosthetic joint infection (PJI) (defined as an infection occurring after 3 months in an otherwise well functioning implant). The rate of infection observed was higher than expected, almost 4 times higher (5.6%) compared to previous historical cohorts from our institution (1.3%). This high risk of infection in patients with DePuy ASR implants requires further study but we theorize that the increased prevalence of infection could be due to a combination of particulate debris, molecular (rather than particulate) effects of Co and Cr ions on soft tissues, and/or products of corrosion that may change the local environment predisposing to infection. PMID:24851788

  17. Poor short term outcome with a metal-on-metal total hip arthroplasty.

    PubMed

    Levy, Yadin D; Ezzet, Kace A

    2013-08-01

    Metal-on-metal (MoM) bearings for total hip arthroplasty (THA) have come under scrutiny with reports of high failure rates. Clinical outcome studies with several commercially available MoM THA bearings remain unreported. We evaluated 78 consecutive MoM THAs from a single manufacturer in 68 patients. Sixty-six received cobalt-chrome (CoCr) monoblock and 12 received modular titanium acetabular cups with internal CoCr liners. Femoral components were titanium with modular necks. At average 2.1 years postoperatively, 12 THAs (15.4%) demonstrated aseptic failure (10 revisions, 2 revision recommended). All revised hips demonstrated capsular necrosis with positive histology reaction for aseptic lymphocytic vasculitis-associated lesions/adverse local tissue reactions. Prosthetic instability following revision surgery was relatively common. Female gender was a strong risk factor for failure, though smaller cups were not. Both monoblock and modular components fared poorly. Corrosion was frequently observed around the proximal and distal end of the modular femoral necks. PMID:23538122

  18. Long-duration metal-on-metal total hip arthroplasties with low wear of the articulating surfaces.

    PubMed

    Schmalzried, T P; Peters, P C; Maurer, B T; Bragdon, C R; Harris, W H

    1996-04-01

    The 20-year performance of metal-on-metal hip articulations has not been reported. Five McKee-Farrar total hip prostheses and one Sivash prosthesis were obtained at revision surgery after a mean implantation time of 21.3 years. A radiographic, histologic, implant, and wear analysis was performed on these total hip implants with cobalt-chrome metal-on-metal articulations. All cases were associated with femoral component loosening, but the bearing surfaces performed remarkably well. The worst case estimate of combined femoral and acetabular linear wear was 4.2 microns per year, about 25 times less than that typically seen with polyethylene. Metal particles and foreign-body inflammation were seen in all cases, but the volume of reactive tissue was small compared with what is generally seen at revision of hips with a polyethylene acetabular bearing. This may be due to a reduced particle burden or a decreased inflammatory reaction to particulate metal, or both. In addition to articular wear, other sources of metal particles included femoral neck impingement on the acetabular rim, stem burnishing, and corrosion. Prosthetic hip reconstructions can fail for many reasons, including suboptimal femoral stem and/or acetabular cup design and/or fixation. By today's standards, the McKee-Farrar and Sivash stem and acetabular component designs are suboptimal; however, after more than 20 years of use, the metal-on-metal bearing surfaces in these cases demonstrated low wear and do not appear to be the cause of failure. Recent advances in total hip arthroplasty, which include improved implant design, materials, manufacturing, and fixation, combined with a better understanding of the mechanisms of implant loosening and failure, suggest that the cobalt-chrome metal-on-metal bearing be reexamined as an alternative to polyethylene when exceptional durability is required. PMID:8713913

  19. Cutaneous manifestation of metallosis in a metal-on-metal total hip arthroplasty after acetabular liner dissociation.

    PubMed

    Sporer, Scott M; Chalmers, Peter N

    2012-09-01

    In this case report, we describe a cutaneous manifestation of extensive metallosis in a patient 4 months post-metal-on-metal total hip arthroplasty with a Pinnacle cup with dissociation of the liner from the shell and resultant stripe burnishing of the shell and notch wear of the femoral neck. Dissociation of a metal liner has not been previously reported with this implant. Cutaneous metallosis has only been reported once in the literature. Clinicians should heighten their suspicion for metallosis secondary to hardware failure when encountering patients with skin discoloration in the setting of a painful and poorly functioning hip arthroplasty. In patients with failure of a metal-on-metal prosthesis with a modular metal liner in the acetabular component, liner dissociation must be considered. PMID:22397858

  20. Gender is a significant factor for failure of metal-on-metal total hip arthroplasty.

    PubMed

    Latteier, Michael J; Berend, Keith R; Lombardi, Adolph V; Ajluni, Andrew F; Seng, Brian E; Adams, Joanne B

    2011-09-01

    Metal-on-metal (MoM) articulations offers low wear, larger head size, and increased stability. Reports of early failure are troubling and include failure of ingrowth and metal articulation problems such as metallosis, hypersensitivity, pseudotumor, and unexplained pain. This study investigates the survivorship of modern MoM articulations by gender. We reviewed 1589 primary MoM THA in 1363 patients, with minimum 2-year follow-up for 1212 hips. Follow-up averaged 60 months. There were 643 female patients and 719 male patients. The incidence of cup revision was significantly higher in women than in men (8.2% vs 2.7%; P = .0000), as was incidence of aseptic loosening (4.3% vs 1.1%; P = .0006), and failure for metal-bearing complications (2.2% vs 0.6%; P = .0126). There appear to be gender factors influencing the success of MoM THA, which may include hormonal, anatomic, or functional differences. PMID:21641761

  1. Spectral and total temperature-dependent emissivities of few-layer structures on a metallic substrate.

    PubMed

    Blandre, Etienne; Chapuis, Pierre-Olivier; Vaillon, Rodolphe

    2016-01-25

    We investigate the thermal radiative emission of few-layer structures deposited on a metallic substrate and its dependence on temperature with the Fluctuational Electrodynamics approach. We highlight the impact of the variations of the optical properties of metallic layers on their temperature-dependent emissivity. Fabry-Pérot spectral selection involving at most two transparent layers and one thin reflective layer leads to well-defined peaks and to the amplification of the substrate emission. For a single Fabry-Pérot layer on a reflective substrate, an optimal thickness that maximizes the emissivity of the structure can be determined at each temperature. A thin lossy layer deposited on the previous structure can enhance interference phenomena, and the analysis of the participation of each layer to the emission shows that the thin layer is the main source of emission. Eventually, we investigate a system with two Fabry-Pérot layers and a metallic thin layer, and we show that an optimal architecture can be found. The total hemispherical emissivity can be increased by one order of magnitude compared to the substrate emissivity. PMID:26832589

  2. Effect of [Fe 2+/total metal] on treatment of heavy metals from laboratory wasteliquid by ferrite process

    NASA Astrophysics Data System (ADS)

    Huang, Yuh-Jeen; Tu, Chiu-Hui; Chien, Yi-Chi; Chen, Hung-Ta

    2006-11-01

    In this study, the X-ray absorption near-edge structure shows that poisonous Cr 6+ in the laboratory wasteliquid were reduced to Cr 3+ by adding Fe 2+ at [Fe 2+/total metal, mole ratio higher than 4:1. The X-ray diffraction analysis shows that greater the [Fe 2+/total metal] mole ratios used (such as 6:1, 10:1, 20:1 and 30:1), the more spinel-structured ferrites were formed (0.26, 0.30, 0.48 and 0.59). When [Fe 2+/total metal] mole ratio was larger than 20:1, the saturation magnetization and coercive field were about 5.21 emu/g and 6.2 kOe, respectively. The ferrite precipitates could be recovered as magnitude materials. However, the TCLP test result was beyond the standard of EPA when the [Fe 2+/total metal] mole ratio was 30:1. The optimum operation for the laboratory wasteliquid by ferrite process in the [Fe 2+/total metal] mole ratio was 20:1.

  3. Particle characterisation and cytokine expression in failed small-diameter metal-on-metal total hip arthroplasties.

    PubMed

    Singh, G; Nuechtern, J V; Meyer, H; Fiedler, G M; Awiszus, F; Junk-Jantsch, S; Bruegel, M; Pflueger, G; Lohmann, C H

    2015-07-01

    The peri-prosthetic tissue response to wear debris is complex and influenced by various factors including the size, area and number of particles. We hypothesised that the 'biologically active area' of all metal wear particles may predict the type of peri-prosthetic tissue response. Peri-prosthetic tissue was sampled from 21 patients undergoing revision of a small diameter metal-on-metal (MoM) total hip arthroplasty (THA) for aseptic loosening. An enzymatic protocol was used for tissue digestion and scanning electron microscope was used to characterise particles. Equivalent circle diameters and particle areas were calculated. Histomorphometric analyses were performed on all tissue specimens. Aspirates of synovial fluid were collected for analysis of the cytokine profile analysis, and compared with a control group of patients undergoing primary THA (n = 11) and revision of a failed ceramic-on-polyethylene arthroplasty (n = 6). The overall distribution of the size and area of the particles in both lymphocyte and non-lymphocyte-dominated responses were similar; however, the subgroup with lymphocyte-dominated peri-prosthetic tissue responses had a significantly larger total number of particles. 14 cytokines (interleukin (IL)-1ß, IL-2, IL-4, IL-5, IL-6, IL-10, IL-13, IL-17, interferon (IFN)-γ, and IFN-gamma-inducible protein 10), chemokines (macrophage inflammatory protein (MIP)-1α and MIP-1ß), and growth factors (granulocyte macrophage colony stimulating factor (GM-CSF) and platelet derived growth factor) were detected at significantly higher levels in patients with metal wear debris compared with the control group. Significantly higher levels for IL-1ß, IL-5, IL-10 and GM-CSF were found in the subgroup of tissues from failed MoM THAs with a lymphocyte-dominated peri-prosthetic response compared with those without this response. These results suggest that the 'biologically active area' predicts the type of peri-prosthetic tissue response. The cytokines IL-1ß, IL-5

  4. Mortality rates at 10 years after metal-on-metal hip resurfacing compared with total hip replacement in England: retrospective cohort analysis of hospital episode statistics

    PubMed Central

    Kendal, Adrian R; Prieto-Alhambra, Daniel; Arden, Nigel K; Judge, Andrew

    2013-01-01

    Objectives To compare 10 year mortality rates among patients undergoing metal-on-metal hip resurfacing and total hip replacement in England. Design Retrospective cohort study. Setting English hospital episode statistics database linked to mortality records from the Office for National Statistics. Population All adults who underwent primary elective hip replacement for osteoarthritis from April 1999 to March 2012. The exposure of interest was prosthesis type: cemented total hip replacement, uncemented total hip replacement, and metal-on-metal hip resurfacing. Confounding variables included age, sex, Charlson comorbidity index, rurality, area deprivation, surgical volume, and year of operation. Main outcome measures All cause mortality. Propensity score matching was used to minimise confounding by indication. Kaplan-Meier plots estimated the probability of survival up to 10 years after surgery. Multilevel Cox regression modelling, stratified on matched sets, described the association between prosthesis type and time to death, accounting for variation across hospital trusts. Results 7437 patients undergoing metal-on-metal hip resurfacing were matched to 22 311 undergoing cemented total hip replacement; 8101 patients undergoing metal-on-metal hip resurfacing were matched to 24 303 undergoing uncemented total hip replacement. 10 year rates of cumulative mortality were 271 (3.6%) for metal-on-metal hip resurfacing versus 1363 (6.1%) for cemented total hip replacement, and 239 (3.0%) for metal-on-metal hip resurfacing versus 999 (4.1%) for uncemented total hip replacement. Patients undergoing metal-on-metal hip resurfacing had an increased survival probability (hazard ratio 0.51 (95% confidence interval 0.45 to 0.59) for cemented hip replacement; 0.55 (0.47 to 0.65) for uncemented hip replacement). There was no evidence for an interaction with age or sex. Conclusions Patients with hip osteoarthritis undergoing metal-on-metal hip resurfacing have reduced mortality in

  5. Comparison of synovial fluid, urine, and serum ion levels in metal-on-metal total hip arthroplasty at a minimum follow-up of 18 years.

    PubMed

    Lass, Richard; Grübl, Alexander; Kolb, Alexander; Stelzeneder, David; Pilger, Alexander; Kubista, Bernd; Giurea, Alexander; Windhager, Reinhard

    2014-09-01

    Diagnosis of adverse reactions to metal debris in metal-on-metal hip arthroplasty is a multifactorial process. Systemic ion levels are just one factor in the evaluation and should not be relied upon solely to determine the need for revision surgery. Furthermore, the correlation between cobalt or chromium serum, urine, or synovial fluid levels and adverse local tissue reactions is still incompletely understood. The hypothesis was that elevated serum and urine metal-ion concentrations are associated with elevated local metal-ion concentrations in primary total hip arthroplasties (THA) and with failure of metal-on-metal articulations in the long-term. In our present study, we evaluated these concentrations in 105 cementless THA with metal-on-metal articulating surfaces with small head diameter at a minimum of 18 years postoperatively. Spearman correlation showed a high correlation between the joint fluid aspirate concentration of cobalt and chromium with the serum cobalt (r = 0.81) and chromium level (r = 0.77) in patients with the THA as the only source of metal-ions. In these patients serum metal-ion analysis is a valuable method for screening. In patients with more than one source of metal or renal insufficiency additional investigations, like joint aspirations are an important tool for evaluation of wear and adverse tissue reactions in metal-on-metal THA. PMID:24841922

  6. Prediction of contact mechanics in metal-on-metal Total Hip Replacement for parametrically comprehensive designs and loads.

    PubMed

    Donaldson, Finn E; Nyman, Edward; Coburn, James C

    2015-07-16

    Manufacturers and investigators of Total Hip Replacement (THR) bearings require tools to predict the contact mechanics resulting from diverse design and loading parameters. This study provides contact mechanics solutions for metal-on-metal (MoM) bearings that encompass the current design space and could aid pre-clinical design optimization and evaluation. Stochastic finite element (FE) simulation was used to calculate the head-on-cup contact mechanics for five thousand combinations of design and loading parameters. FE results were used to train a Random Forest (RF) surrogate model to rapidly predict the contact patch dimensions, contact area, pressures and plastic deformations for arbitrary designs and loading. In addition to widely observed polar and edge contact, FE results included ring-polar, asymmetric-polar, and transitional categories which have previously received limited attention. Combinations of design and load parameters associated with each contact category were identified. Polar contact pressures were predicted in the range of 0-200 MPa with no permanent deformation. Edge loading (with subluxation) was associated with pressures greater than 500 MPa and induced permanent deformation in 83% of cases. Transitional-edge contact (with little subluxation) was associated with intermediate pressures and permanent deformation in most cases, indicating that, even with ideal anatomical alignment, bearings may face extreme wear challenges. Surrogate models were able to accurately predict contact mechanics 18,000 times faster than FE analyses. The developed surrogate models enable rapid prediction of MoM bearing contact mechanics across the most comprehensive range of loading and designs to date, and may be useful to those performing bearing design optimization or evaluation. PMID:25980556

  7. Contact mechanics of modular metal-on-polyethylene total hip replacement under adverse edge loading conditions.

    PubMed

    Hua, Xijin; Li, Junyan; Wang, Ling; Jin, Zhongmin; Wilcox, Ruth; Fisher, John

    2014-10-17

    Edge loading can negatively impact the biomechanics and long-term performance of hip replacements. Although edge loading has been widely investigated for hard-on-hard articulations, limited work has been conducted for hard-on-soft combinations. The aim of the present study was to investigate edge loading and its effect on the contact mechanics of a modular metal-on-polyethylene (MoP) total hip replacement (THR). A three-dimensional finite element model was developed based on a modular MoP bearing. Different cup inclination angles and head lateral microseparation were modelled and their effect on the contact mechanics of the modular MoP hip replacement were examined. The results showed that lateral microseparation caused loading of the head on the rim of the cup, which produced substantial increases in the maximum von Mises stress in the polyethylene liner and the maximum contact pressure on both the articulating surface and backside surface of the liner. Plastic deformation of the liner was observed under both standard conditions and microseparation conditions, however, the maximum equivalent plastic strain in the liner under microseparation conditions of 2000 µm was predicted to be approximately six times that under standard conditions. The study has indicated that correct positioning the components to avoid edge loading is likely to be important clinically even for hard-on-soft bearings for THR. PMID:25218504

  8. Contact mechanics of modular metal-on-polyethylene total hip replacement under adverse edge loading conditions

    PubMed Central

    Hua, Xijin; Li, Junyan; Wang, Ling; Jin, Zhongmin; Wilcox, Ruth; Fisher, John

    2014-01-01

    Edge loading can negatively impact the biomechanics and long-term performance of hip replacements. Although edge loading has been widely investigated for hard-on-hard articulations, limited work has been conducted for hard-on-soft combinations. The aim of the present study was to investigate edge loading and its effect on the contact mechanics of a modular metal-on-polyethylene (MoP) total hip replacement (THR). A three-dimensional finite element model was developed based on a modular MoP bearing. Different cup inclination angles and head lateral microseparation were modelled and their effect on the contact mechanics of the modular MoP hip replacement were examined. The results showed that lateral microseparation caused loading of the head on the rim of the cup, which produced substantial increases in the maximum von Mises stress in the polyethylene liner and the maximum contact pressure on both the articulating surface and backside surface of the liner. Plastic deformation of the liner was observed under both standard conditions and microseparation conditions, however, the maximum equivalent plastic strain in the liner under microseparation conditions of 2000 µm was predicted to be approximately six times that under standard conditions. The study has indicated that correct positioning the components to avoid edge loading is likely to be important clinically even for hard-on-soft bearings for THR. PMID:25218504

  9. Cancer incidence and causes of death among total hip replacement patients: a review based on Nordic cohorts with a special emphasis on metal-on-metal bearings.

    PubMed

    Visuri, T I; Pukkala, E; Pulkkinen, P; Paavolainen, P

    2006-02-01

    All patients with total hip arthroplasty (THA) are exposed to soluble or particulate forms of Co and Cr. Adverse effects of these wear products are not known. Data from Nordic registries is used to estimate adverse effects on a large scale, based mostly on metal-on-polyethylene bearings. Cancer incidence was in line with the general population when the patients were operated on for all indications and significantly decreased when the indication was primary osteoarthritis. Stomach cancer and colorectal cancers were significantly reduced and prostate cancer and skin melanoma significantly increased. There was no significant excess of cancer in target organs, i.e. liver, kidney, or haematopoietic cancers. THA patients had reduced mortality and extended life expectancy compared with standard Nordic populations. All-site cancer incidence of the first-generation metal-on-metal McKee-Farrar patients operated on for primary osteoarthritis was in line with the general population after follow-up for up to 28 years. General mortality of these patients was also reduced and they also had an extended life expectancy. Temporary increases in haematopoietic cancers at different follow-up periods were seen in some cohorts. This malignancy deserves a special record linkage monitoring while large numbers of young patients are provided with the second generation of metal-on-metal prostheses. PMID:16669405

  10. The influence of metallic shell deformation on the contact mechanics of a ceramic-on-ceramic total hip arthroplasty.

    PubMed

    Qiu, Changdong; Wang, Ling; Li, Dichen; Jin, Zhongmin

    2016-01-01

    Total hip arthroplasty of ceramic-on-ceramic bearing combinations is increasingly used clinically. The majority of these implants are used with cementless fixation that a metal-backing shell is press-fitted into the pelvic bone. This usually results in the deformation of the metallic shell, which may also influence the ceramic liner deformation and consequently the contact mechanics between the liner and the femoral head under loading. The explicit dynamic finite element method was applied to model the implantation of a cementless ceramic-on-ceramic with a titanium shell and subsequently to investigate the effect of the metallic shell deformation on the contact mechanics. A total of three impacts were found to be necessary to seat the titanium alloy shell into the pelvic bone cavity with a 1 mm diameter interference and a 1.3 kg impactor at 4500 mm s(-1) velocity. The maximum deformation of the metallic shell was found to be 160 µm in the antero-superior and postero-inferior direction and 97 µm in the antero-inferior and postero-superior direction after the press-fit. The corresponding values were slightly reduced to 67 and 45 µm after the ceramic liner was inserted and then modified to 74 and 43 µm under loading, respectively. The maximum deformation and the maximum principal stress of the ceramic liner were 31 µm and 144 MPa (tensile stress), respectively, after it was inserted into the shell and further increased to 52 µm and 245 MPa under loading. This research highlights the importance of the press-fit of the metallic shell on the contact mechanics of the ceramic liner for ceramic-on-ceramic total hip arthroplasties and potential clinical performances. PMID:26511269

  11. Surface and Subsurface Analyses of Metal-on-Polyethylene Total Hip Replacement Retrievals.

    PubMed

    Vuong, Vicky; Pettersson, Maria; Persson, Cecilia; Larsson, Sune; Grandfield, Kathryn; Engqvist, Håkan

    2016-05-01

    Metal-on-polyethylene (MoP) articulations are one of the most reliable implanted hip prostheses. Unfortunately, long-term failure remains an obstacle to the service life. There is a lack of higher resolution research investigating the metallic surface component of MoP hip implants. This study investigates the surface and subsurface features of metallic cobalt chromium molybdenum alloy (CoCrMo) femoral head components from failed MoP retrievals. Unused prostheses were used for comparison to differentiate between wear-induced defects and imperfections incurred during implant manufacturing. The predominant scratch morphology observed on the non-implanted references was shallow and linear, whereas the scratches on the retrievals consisted of largely nonlinear, irregular scratches of varying depth (up to 150 nm in retrievals and up to 60 nm in reference samples). Characteristic hard phases were observed on the surface and subsurface material of the cast samples. Across all samples, a 100-400 nm thick nanocrystalline layer was visible in the immediate subsurface microstructure. Although observation of the nanocrystalline layer has been reported in metal-on-metal articulations, its presence in MoP retrievals and unimplanted prostheses has not been extensively examined. The results suggest that manufacturing-induced surface and subsurface microstructural features are present in MoP hip prostheses prior to implantation and naturally, these imperfections may influence the in vivo wear processes after implantation. PMID:26399989

  12. Adverse reaction to metal debris after ReCap-M2A-Magnum large-diameter-head metal-on-metal total hip arthroplasty

    PubMed Central

    2013-01-01

    Background and purpose The clinical findings of adverse reaction to metal debris (ARMD) following large-diameter-head metal-on-metal total hip arthroplasty (LDH MoM THA) may include periarticular fluid collections, soft tissue masses, and gluteal muscle necrosis. The ReCap-M2a-Magnum LDH MoM THA was the most commonly used hip device at our institution from 2005 to 2012. We assessed the prevalence of and risk factors for ARMD with this device. Methods 74 patients (80 hips) had a ReCap-M2a-Magnum LDH MoM THA during the period August 2005 to December 2006. These patients were studied with hip MRI, serum chromium and cobalt ion measurements, the Oxford hip score questionnaire, and by clinical examination. The prevalence of ARMD was recorded and risk factors for ARMD were assessed using logistic regression models. The mean follow-up time was 6.0 (5.5–6.7) years. Results A revision operation due to ARMD was needed by 3 of 74 patients (3 of 80 hips). 8 additional patients (8 hips) had definite ARMD, but revision was not performed. 29 patients (32 hips) were considered to have a probable or possible ARMD. Altogether, 43 of 80 hips had a definite, probable, or possible ARMD and 34 patients (37 hips) were considered not to have ARMD. In 46 of 78 hips, MRI revealed a soft tissue mass or a collection of fluid (of any size). The symptoms clicking in the hip, local hip swelling, and a feeling of subluxation were associated with ARMD. Interpretation ARMD is common after ReCap-M2a-Magnum total hip arthroplasty, and we discourage the use of this device. Asymptomatic patients with a small fluid collection on MRI may not need instant revision surgery but must be followed up closely. PMID:24171688

  13. Effect of acanthocephalan infection on metal, total protein and metallothionein concentrations in European chub from a Sava River section with low metal contamination.

    PubMed

    Filipović Marijić, Vlatka; Vardić Smrzlić, Irena; Raspor, Biserka

    2013-10-01

    In the present study, the importance of considering fish intestinal parasites i.e. the acanthocephalans in metal exposure assessment was estimated under low metal contamination conditions. Two acanthocephalan species, Pomphorhynchus laevis and Acanthocephalus anguillae were examined in 59 specimens of European chub (Squalius cephalus L.) sampled at 5 locations along the Sava River, Croatia. Concentrations of essential (Cu, Mn) and non-essential (Ag, Cd, Pb) metals were higher in intestinal parasites than chub gastrointestinal tissue, but levels of essential metals Fe and Zn were comparable or lower in parasites, respectively. The highest accumulation in both acanthocephalan species was found for non-essential metals and followed the order: Ag>Pb>Cd. Higher infection intensity with P. laevis allowed us to present their spatial metal distribution and evaluate the influence of P. laevis on metal levels and sub-cellular biological responses (total protein and metallothionein levels) in the host infected with P. laevis. Even in the river section with low metal contamination, parasitism affected metal levels, resulting in lower Cu, Cd and Pb concentrations in chub infected with P. laevis than in uninfected chub. Although total protein and metallothionein levels remained constant in infected and uninfected chub, acanthocephalans should be considered a potential confounding factor in metal exposure assessments. Moreover, P. laevis-chub system can be suggested as an appropriate tool in biomonitoring, since in both species increased Cu and Cd concentrations towards the downstream locations were found. Higher Cu and Cd levels in P. laevis suggest acanthocephalans to be sensitive bioindicators if low metal levels have to be detected. PMID:23856403

  14. [Effect analysis on the two total load control methods for poisonous heavy metals].

    PubMed

    Fu, Guo-Wei

    2012-12-01

    Firstly it should be made clear that implementation of source total load control for the first type of pollutants is necessary for environmental pollution control legislation and economic structure regulation. This kind of surveillance method has been more practical to be implemented since the Manual of the Industry Discharge Coefficient of First National Pollution Sources Investigation was published. The source total load control and water environment total load control are independent of each other and none of them is redundant, on the other side they can be complementary to each other. In the present, some local planning managers are blurring and confusing the contents and styles of the two surveillance methods. They just use the water total load control to manage all the pollutants, and source total load control is discarded, which results in the loss of control for the first type of pollutants especially for the drinking water source surveillance. There is a big difference between the water quality standards and the water environmental background concentration values for the first type of pollutants in the Environmental quality standard for surface water (GB 3838-88), which means that there are problems such as "relaxing the pollutant discharge permit" and "risk induced by valence state change". Taking an enterprise with 10t electrolytic lead production capacity as an example, there is a big difference between the allowable lead discharged loads by the two total load surveillance methods. In summary, it will bring a lot of harmful effects if the water total load control is implemented for the two types of pollutants, so the source total load control and water environmental total load control should be implemented strictly at the same time. PMID:23379176

  15. Evaluation of the wear properties of a metal-on-metal total joint replacement system and in vitro macrophage response to resultant wear particles

    NASA Astrophysics Data System (ADS)

    St. John, Kenneth Raymond

    The wear of the polyethylene in total joint prostheses has been a source of morbidity and early device failure which has been extensively reported in the last ten to twelve years. While research continues to attempt to reduce the wear of polyethylene joint bearing surfaces by modifications in polymer processing, there is a renewed interest in the use of metal-on-metal bearing couples for hip replacement devices. This study investigated the in vitro wear resistance of two cobalt/chromium/molybdenum alloys, which differed primarily in the carbon content, as potential alloys for use in such a metal-on-metal hip bearing couple. The results showed that the alloy with the higher (0.25%) carbon content was more wear resistant and this alloy was chosen for testing in a hip simulator system which modeled the loads and motions which might be exerted on a clinically implanted hip replacement. Comparison of the results of metal-on-polyethylene specimens to metal-on-metal specimens showed that the volumetric wear of the metal-on-polyethylene bearing couple over 5,000,000 cycles was 110--180 times as great as that for the metal bearing couple. Polyethylene and metal particles retrieved from either pin-on-disk testing lubricant or hip simulator testing lubricant were cleaned and examined for consistency with the particles reported by other laboratories for particles from periprosthetic tissues and found to be similar. The particles were then added to macrophage (J774a) cell cultures and the release of Prostaglandin E2, Interleukin-6, and Tumor Necrosis Factor alpha measured for each experiment in response to the particles. The cell mediators released by the cells was found to correlate with the dosage of particles and the chemical identity of the particles. Most of the cellular response to the polyethylene particles seemed to be as a result of phagocytosis of the particles while most of the response to metal particles seemed to be related to cytotoxicity of the particles. Based

  16. Increased Mortality in Metal-on-Metal versus Non-Metal-on-Metal Primary Total Hip Arthroplasty at 10 Years and Longer Follow-Up: A Systematic Review and Meta-Analysis

    PubMed Central

    Meessen, J. M. T. A.; Fiocco, M.; van der Heide, H. J. L.; Sedrakyan, A.; Nelissen, R. G. H. H.

    2016-01-01

    Importance There are concerns about increased mortality in patients with metal-on-metal bearings in total hip arthroplasty (THA). Objective To determine the mortality and the morbidity in patients with metal-on-metal articulations (MOM THA) compared to patients with non-metal-on-metal articulations (non-MOM THA) after primary total hip arthroplasty. Data Sources Search of PubMed, MEDLINE, EMBASE, Web of Science, Cochrane, CINAHL, AcademicSearchPremier, ScienceDirect, Wiley and clinical trial registers through March 2015, augmented by a hand search of references from the included articles. No language restrictions were applied. Study Selection Two reviewers screened and identified randomised controlled trials and observational studies of primary total hip arthroplasty comparing MOM THA with non-MOM THA. Data Extraction and Synthesis Two reviewers independently extracted study data and assessed risk of bias. Risk differences (RD) were calculated with random effect models. Meta-regression was used to explore modifying factors. Main Outcomes and Measures Difference in mortality and difference in morbidity expressed as revisions and medical complications between patients with MOM THA and non-MOM THA. Results Forty-seven studies were included, comprising 4,000 THA in randomised trials and over 500,000 THA in observational studies. For mortality, random effects analysis revealed a higher pooled RD of 0.7%, 95%, confidence interval (CI) [0.0%, 2.3%], I-square 42%; the heterogeneity was explained by differences in follow-up. When restricted to studies with long term follow-up (i.e. 10 years or more), the RD for mortality was 8.5%, 95%, CI [5.8%, 11.2%]; number needed to treat was 12. Further subgroup analyses and meta-regression random effects models revealed no evidence for other moderator variables (study level covariates, e.g. resurfacing vs. non-resurfacing MOM) than follow-up duration. The quality of the evidence presented in this meta-analysis was characterized as

  17. Tribo-biological deposits on the articulating surfaces of metal-on-polyethylene total hip implants retrieved from patients

    PubMed Central

    Cui, Zhiwei; Tian, Yi-Xing; Yue, Wen; Yang, Lei; Li, Qunyang

    2016-01-01

    Artificial total hip arthroplasty (THA) is one of the most effective orthopaedic surgeries that has been used for decades. However, wear of the articulating surfaces is one of the key failure causes limiting the lifetime of total hip implant. In this paper, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were employed to explore the composition and formation mechanism of the tribo-layer on the articulating surfaces of metal-on-polyethylene (MoPE) implants retrieved from patients. Results showed that, in contrast to conventional understanding, the attached tribo-layer contained not only denatured proteins but also a fraction of polymer particles. The formation of the tribo-layer was believed to relate to lubrication regime, which was supposed to be largely affected by the nature of the ultra-high-molecule-weight-polyethylene (UHMWPE). Wear and formation of tribo-layer could be minimized in elasto-hydrodynamic lubrication (EHL) regime when the UHMWPE was less stiff and have a morphology containing micro-pits; whereas the wear was more severe and tribo-layer formed in boundary lubrication. Our results and analyses suggest that enhancing interface lubrication may be more effective on reducing wear than increasing the hardness of material. This finding may shed light on the design strategy of artificial hip joints. PMID:27345704

  18. Tribo-biological deposits on the articulating surfaces of metal-on-polyethylene total hip implants retrieved from patients

    NASA Astrophysics Data System (ADS)

    Cui, Zhiwei; Tian, Yi-Xing; Yue, Wen; Yang, Lei; Li, Qunyang

    2016-06-01

    Artificial total hip arthroplasty (THA) is one of the most effective orthopaedic surgeries that has been used for decades. However, wear of the articulating surfaces is one of the key failure causes limiting the lifetime of total hip implant. In this paper, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were employed to explore the composition and formation mechanism of the tribo-layer on the articulating surfaces of metal-on-polyethylene (MoPE) implants retrieved from patients. Results showed that, in contrast to conventional understanding, the attached tribo-layer contained not only denatured proteins but also a fraction of polymer particles. The formation of the tribo-layer was believed to relate to lubrication regime, which was supposed to be largely affected by the nature of the ultra-high-molecule-weight-polyethylene (UHMWPE). Wear and formation of tribo-layer could be minimized in elasto-hydrodynamic lubrication (EHL) regime when the UHMWPE was less stiff and have a morphology containing micro-pits; whereas the wear was more severe and tribo-layer formed in boundary lubrication. Our results and analyses suggest that enhancing interface lubrication may be more effective on reducing wear than increasing the hardness of material. This finding may shed light on the design strategy of artificial hip joints.

  19. Tribo-biological deposits on the articulating surfaces of metal-on-polyethylene total hip implants retrieved from patients.

    PubMed

    Cui, Zhiwei; Tian, Yi-Xing; Yue, Wen; Yang, Lei; Li, Qunyang

    2016-01-01

    Artificial total hip arthroplasty (THA) is one of the most effective orthopaedic surgeries that has been used for decades. However, wear of the articulating surfaces is one of the key failure causes limiting the lifetime of total hip implant. In this paper, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were employed to explore the composition and formation mechanism of the tribo-layer on the articulating surfaces of metal-on-polyethylene (MoPE) implants retrieved from patients. Results showed that, in contrast to conventional understanding, the attached tribo-layer contained not only denatured proteins but also a fraction of polymer particles. The formation of the tribo-layer was believed to relate to lubrication regime, which was supposed to be largely affected by the nature of the ultra-high-molecule-weight-polyethylene (UHMWPE). Wear and formation of tribo-layer could be minimized in elasto-hydrodynamic lubrication (EHL) regime when the UHMWPE was less stiff and have a morphology containing micro-pits; whereas the wear was more severe and tribo-layer formed in boundary lubrication. Our results and analyses suggest that enhancing interface lubrication may be more effective on reducing wear than increasing the hardness of material. This finding may shed light on the design strategy of artificial hip joints. PMID:27345704

  20. Wear simulation of a polyethylene-on-metal cervical total disc replacement under different concentrations of bovine serum lubricant.

    PubMed

    Hyde, P J; Fisher, J; Hall, R M

    2016-05-01

    Metal-on-polyethylene total disc replacements have been an alternative to spinal fusion in the lumbar spine under certain indications for more than a decade. Recently, cervical total disc replacement has also become an alternative to cervical fusion. Knowledge acquired from years of in vitro simulator studies on other joint replacements has highlighted the risks associated with premature wear due to unforeseen adverse clinical conditions and the effect of particulate debris on surrounding natural tissues. Having no evidence of the type and composition of the lubricating fluid that will result after spinal arthroplasty, a study on the effects of lubricant serum concentration was undertaken. The wear rate was shown to be inversely proportional to protein content of the serum over a range of 50%-3% bovine serum to water concentration. PMID:27160565

  1. Total Hip Arthroplasty Using Metal Head on a Highly Cross-linked Polyethylene Liner

    PubMed Central

    Kim, Min-Yook; Park, Ji-Hoon; Lee, Jung-Ho

    2015-01-01

    Purpose This retrospective study was performed to evaluate the clinical results and measure polyethylene liner wear in total hip arthroplasty (THA) with highly cross-linked polyethylene. Materials and Methods Except for patients who had died or were unable to have follow-up at least 2 years, 60 of 78 hips that underwent THA were included this study. The mean age was 64.5 years (range, 25-81 years) and the mean body mass index (BMI) was 23.0 kg/m2 (18.1-32.3 kg/m2). Diagnosis at the time of the operation was osteonecrois of the femoral head in 28 hips, primary osteoarthritis in 14, hip fracture in 13, and other diseases in 5. The mean follow-up period was 3.8 years (2.1-7.1 years). Harris hip score (HHS) was reviewed before THA and at the last follow-up. On the anteroposterior pelvic radiographs, acetabular cup inclination and ante-version were also measured. The annual linear wear rate was measured using Livermore's method on the radiographs. Results The mean HHS was 60.1 (28-94) before operation and 90.4 (47-100) at the last follow-up. In the immediate post-operation, the average inclination and anteversion angles of the acetabular cups were 46.3° (standard deviation, ±6.7°) and, 21.4°(±10.1°) respectively. The mean of the annual linear polyethylene wear was 0.079 mm/year (0.001-0.291 mm/year). Age, gender and BMI were not statistically related to linear polyethylene wear but the period of follow-up and the acetabular cup's inclination showed significant negative and positive correlation respectively. Conclusion The wear rate of a highly cross-linked polyethylene was shown to correlate negatively with duration of follow-up. However, our study was based on a short-term follow-up, so a long-term follow-up study is necessary in the future. PMID:27536629

  2. Effects of metals on the total lipid content in the gypsy moth (Lymantria dispar, Lymantriidae, Lepid.) and its hemolymph

    SciTech Connect

    Ortel, J.

    1995-08-01

    Previous work on the gypsy moth, Lymantria dispar, was focused on the influence of Cd, Pb, Cu and Zn on its life cycle (diverse vitality parameters), stage-specific accumulation potential and implications on one of its parasitoids Glyptapanteles liparidis. Results of these studies suggested that metal exposure of L. dispar at NOEC (No-Observed-Effect-concentration) levels may influence its hemolymph composition. We decided, therefore, to analyze the hemolymph composition for the main substance classes protein, lipids and carbohydrates of fourth instar larvae of L. dispar exposed to concentrations of Cd, Pb, Cu and Zn in the range of NOECs determined by Gintenreiter et al. (1993a). This study presents the first results of the determination of lipid concentration in the hemolymph of fourth instar larvae as well as of total lipid content of the corresponding larvae. 14 refs., 2 figs.

  3. Does Choice of Head Size and Neck Geometry Affect Stem Migration in Modular Large-Diameter Metal-on-Metal Total Hip Arthroplasty? A Preliminary Analysis

    PubMed Central

    Georgiou, CS; Evangelou, KG; Theodorou, EG; Provatidis, CG; Megas, PD

    2012-01-01

    Due to their theoretical advantages, hip systems combining modular necks and large diameter femoral heads have gradually gained popularity. However, among others, concerns regarding changes in the load transfer patterns were raised. Recent stress analyses have indeed shown that the use of modular necks and big femoral heads causes significant changes in the strain distribution along the femur. Our original hypothesis was that these changes may affect early distal migration of a modular stem. We examined the effect of head diameter and neck geometry on migration at two years of follow-up in a case series of 116 patients (125 hips), who have undergone primary Metal-on-Metal total hip arthroplasty with the modular grit-blasted Profemur®E stem combined with large-diameter heads (>36 mm). We found that choice of neck geometry and head diameter has no effect on stem migration. A multivariate regression analysis including the potential confounding variables of the body mass index, bone quality, canal fill and stem positioning revealed only a negative correlation between subsidence and canal fill in midstem area. Statistical analysis, despite its limitations, did not confirm our hypothesis that choice of neck geometry and/or head diameter affects early distal migration of a modular stem. However, the importance of correct stem sizing was revealed. PMID:23284597

  4. Comparison of Whole-Blood Metal Ion Levels Among Four Types of Large-Head, Metal-on-Metal Total Hip Arthroplasty Implants: A Concise Follow-up, at Five Years, of a Previous Report.

    PubMed

    Hutt, Jonathan; Lavigne, Martin; Lungu, Eugen; Belzile, Etienne; Morin, François; Vendittoli, Pascal-André

    2016-02-17

    Few studies of total hip arthroplasty (THA) implants with a large-diameter femoral head and metal-on-metal design have directly compared the progression of metal ion levels over time and the relationship to complications. As we previously reported, 144 patients received one of four types of large-diameter-head, metal-on-metal THA designs (Durom, Birmingham, ASR XL, or Magnum implants). Cobalt, chromium, and titanium ion levels were measured over five years. We compared ion levels and clinical results over time. The Durom group showed the highest levels of cobalt (p ≤ 0.002) and titanium ions (p ≤ 0.03). Both the Durom and Birmingham groups demonstrated significant ongoing cobalt increases up to five years. Eight patients (seven with a Durom implant and one with a Birmingham implant) developed adverse local tissue reaction. Six Durom implants and one Birmingham implant required revision, with one pseudotumor under surveillance at the time of the most recent follow-up. We found that ion generation and related complications varied among designs. More concerning was that, for some designs, ion levels continued to increase. Coupling a cobalt-chromium adapter sleeve to an unmodified titanium femoral trunnion along with a large metal-on-metal bearing may explain the poor performances of two of the designs in the current study. PMID:26888673

  5. Clinical outcome study and radiological findings of Zweymuller metal on metal total hip arthroplasty. a follow-up of 6 to 15 years.

    PubMed

    Paleochorlidis, Ilias S; Badras, Leonidas S; Skretas, Efstathios F; Georgaklis, Vasilios A; Karachalios, Theofilos S; Malizos, Konstantinos N

    2009-01-01

    We report the clinical and radiological outcome of 99 Zweymuller metal on metal total hip arthroplasties in 84 patients followed up prospectively for a mean period of 9.5 (range, 6-15) years. There were 29 (34.5%) male and 55 (65.5%) female patients with a mean age of 62.85 years (range, 50-70 years) at the time of surgery. All patients had osteoarthritis. One acetabular component and one stem were revised due to aseptic loosening. One femoral stem was revised due to a periprosthetic fracture. HHS score improved from a preoperative mean of 62.56 points (SD 8.87) to a final postoperative follow-up mean of 93.48 (SD 7.7). Cumulative success rate for both implants at 13 years, with aseptic loosening as the end point, was 97.05%, while for both implants at 13 years, with revision for any reason as the end point, it was 91.17%. Satisfactory results were observed with the use of this prosthesis. PMID:20041375

  6. The Latest Lessons Learned from Retrieval Analyses of Ultra-High Molecular Weight Polyethylene, Metal-on-Metal, and Alternative Bearing Total Disc Replacements

    PubMed Central

    Kurtz, Steven M.; Toth, Jeffrey M.; Siskey, Ryan; Ciccarelli, Lauren; MacDonald, Dan; Isaza, Jorge; Lanman, Todd; Punt, Ilona; Steinbeck, Marla; Goffin, Jan; van Ooij, André

    2012-01-01

    Knowledge regarding the in vivo performance and periposthetic tissue response of cervical and lumbar total disc replacements (TDRs) continues to expand. This review addresses the following four main questions: 1) What are the latest lessons learned from polyethylene in large joints and how are they relevant to current TDRs? 2) What are the latest lessons learned regarding adverse local tissue reactions from metal-on-metal, CoCr bearings in large joints and how are they relevant to current TDRs? 3) What advancements have been made in understanding the in vivo performance of alternative biomaterials, such as stainless steel and polycarbonate urethane, for TDRs in the past five years? 4) How has retrieval analysis of all these various artificial disc bearing technologies advanced the state of the art in preclinical testing of TDRs? The study of explanted artificial discs and their associated tissues can help inform bearing selection as well as the design of future generations of disc arthroplasty. Analyzing retrieved artificial discs is also essential for validating preclinical test methods. PMID:22904606

  7. Combined effect of smoking habits and occupational exposure to hard metal on total IgE antibodies

    SciTech Connect

    Shirakawa, T.; Kusaka, Y.; Morimoto, K. )

    1992-06-01

    A survey was made within a population of workers (n = 706) exposed to hard metal dust (an alloy including cobalt), an agent known to cause occupational allergy. Twenty-seven (4 percent) of 733 workers were eliminated from consideration in this study because of atopic status identified prior to starting work in the plant. Using a Phadebas PRIST, the subjects' total IgE levels were determined and related to their smoking and exposure status. Nonexposed male smokers (n = 135) had a higher geometric mean IgE level (39.7 IU/ml) than did nonexposed subjects who had never smoked (33.1 IU/ml; n = 99); those with a higher Brinkman index (greater than 300), a smoking index obtained by multiplying the number of cigarettes per day by the duration of smoking in years, had significantly (p less than 0.05) decreased IgE levels. Although ex-smokers (n = 72) had a higher geometric mean IgE level (73.3 IU/ml) than did those who had never smoked, their serum IgE level declined with age since the time they quit smoking, regardless of their hard metal exposure status. Hard metal (cobalt) exposure may play a significant role as an adjuvant in the production of total IgE. A multivariate analysis demonstrated that hard metal exposure and a smoking habit together arithmetically (p less than 0.05) increased total IgE levels. These two factors may be preventable risk factors for occupational allergy in hard metal workers.

  8. The contact mechanics and occurrence of edge loading in modular metal-on-polyethylene total hip replacement during daily activities.

    PubMed

    Hua, Xijin; Li, Junyan; Jin, Zhongmin; Fisher, John

    2016-06-01

    The occurrence of edge loading in hip joint replacement has been associated with many factors such as prosthetic design, component malposition and activities of daily living. The present study aimed to quantify the occurrence of edge loading/contact at the articulating surface and to evaluate the effect of cup angles and edge loading on the contact mechanics of a modular metal-on-polyethylene (MoP) total hip replacement (THR) during different daily activities. A three-dimensional finite element model was developed based on a modular MoP bearing system. Different cup inclination and anteversion angles were modelled and six daily activities were considered. The results showed that edge loading was predicted during normal walking, ascending and descending stairs activities under steep cup inclination conditions (≥55°) while no edge loading was observed during standing up, sitting down and knee bending activities. The duration of edge loading increased with increased cup inclination angles and was affected by the cup anteversion angles. Edge loading caused elevated contact pressure at the articulating surface and substantially increased equivalent plastic strain of the polyethylene liner. The present study suggested that correct positioning the component to avoid edge loading that may occur during daily activities is important for MoP THR in clinical practice. PMID:27056255

  9. Total Knee Arthroplasty Failure Induced by Metal Hypersensitivity

    PubMed Central

    Gupta, Ryan; Phan, Duy; Schwarzkopf, Ran

    2015-01-01

    Patient: Female, 70 Final Diagnosis: Metal hypersensitivity Symptoms: Joint pain • swelling • instability Medication: — Clinical Procedure: Revision total knee arthroplasty Specialty: Orthopedics and Traumatology Objective: Unusual clinical course Background: Metal hypersensitivity is an uncommon complication after total knee arthroplasty (TKA) that can lead to significant functional impairment and aseptic prosthesis failure. Case Report: We describe a 70-year-old patient who presented with persistent pain, swelling, and instability 2 years after a primary TKA. The patient had a history of metal hypersensitivity following bilateral metal-on-metal total hip arthroplasty (THA) that was revised to ceramic-on-polyethylene implants. Knee radiographs showed severe osteolysis with implant loosening. Serum cobalt was elevated and serum chromium was significantly elevated, while joint aspiration and inflammatory marker levels ruled out a periprosthetic infection. Revision TKA was performed, with intraoperative tissue pathology and postoperative leukocyte transformation testing confirming metal hypersensitivity as the cause for aseptic implant failure. Conclusions: This case report demonstrates the clinical and laboratory signs that suggest metal hypersensitivity in total knee arthroplasty and the potential for joint function restoration with revision surgery. PMID:26278890

  10. Similar incidence of periprosthetic fluid collections after ceramic-on-polyethylene total hip arthroplasties and metal-on-metal resurfacing arthroplasties: results of a screening metal artefact reduction sequence-MRI study.

    PubMed

    Bisseling, P; de Wit, B W K; Hol, A M; van Gorp, M J; van Kampen, A; van Susante, J L C

    2015-09-01

    Patients from a randomised trial on resurfacing hip arthroplasty (RHA) (n = 36, 19 males; median age 57 years, 24 to 65) comparing a conventional 28 mm metal-on-metal total hip arthroplasty (MoM THA) (n = 28, 17 males; median age 59 years, 37 to 65) and a matched control group of asymptomatic patients with a 32 mm ceramic-on-polyethylene (CoP) THA (n = 33, 18 males; median age 63 years, 38 to 71) were cross-sectionally screened with metal artefact reducing sequence-MRI (MARS-MRI) for pseudotumour formation at a median of 55 months (23 to 72) post-operatively. MRIs were scored by consensus according to three different classification systems for pseudotumour formation. Clinical scores were available for all patients and metal ion levels for MoM bearing patients. Periprosthetic lesions with a median volume of 16 mL (1.5 to 35.9) were diagnosed in six patients in the RHA group (17%), one in the MoM THA group (4%) and six in the CoP group (18%). The classification systems revealed no clear differences between the groups. Solid lesions (n = 3) were exclusively encountered in the RHA group. Two patients in the RHA group and one in the MoM THA group underwent a revision for pseudotumour formation. There was no statistically significant relationship between clinical scoring, metal ion levels and periprosthetic lesions in any of the groups. Periprosthetic fluid collections are seen on MARS-MRI after conventional CoP THA and RHA and may reflect a soft-tissue collection or effusion. Currently available MRI classification systems seem to score these collections as pseudotumours, causing an-overestimatation of the incidence of pseudotumours. PMID:26330582

  11. Incomplete seating of a metal-backed alumina liner in ceramic-on-ceramic total hip arthroplasty.

    PubMed

    Carvajal Alba, Jaime A; Schiffman, Eric D; Scully, Sean P; Parvataneni, Hari K

    2010-01-01

    Metal-backed modular ceramic bearing systems using a recessed alumina liner in a titanium sleeve were developed to decrease ceramic chipping or fracture due to femoral neck impingement after total hip arthroplasty (THA). However, malseating of the metal-backed ceramic liner has recently been described. The goal of this study was to assess the prevalence, etiology, and clinical relevance of this event. Between 2005 and 2008, 51 consecutive patients (61 hips) underwent THA with a metal-backed alumina liner housed in a titanium shell. The metal-backed ceramic liner was aligned, seated, and impacted into the shell, and satisfaction in terms of liner stability and seating was confirmed intraoperatively. Postoperative assessment of seating was assessed with standard radiographs. Liner seating was classified as well seated, suspicious, or malseated. Seven liners (11.5%) were found to be malseated and 4 (6.5%) were considered suspicious. Radiographically, there was a gap between the liner and the shell located inferomedially in 4 patients and superolaterally in 3 patients. Two liners subsequently seated at 1 and 3 months postoperatively, respectively. No dislodgement, failures, or adverse events were identified. There were no revision surgeries. The significant percentage of malseated liners were potentially attributed to poor exposure, bony/soft tissue interposition, and surgeon learning curve. PMID:20055343

  12. Pseudotumour incidence, cobalt levels and clinical outcome after large head metal-on-metal and conventional metal-on-polyethylene total hip arthroplasty: mid-term results of a randomised controlled trial.

    PubMed

    van der Veen, H C; Reininga, I H F; Zijlstra, W P; Boomsma, M F; Bulstra, S K; van Raay, J J A M

    2015-11-01

    We compared the incidence of pseudotumours after large head metal-on-metal (MoM) total hip arthroplasty (THA) with that after conventional metal-on-polyethylene (MoP) THA and assessed the predisposing factors to pseudotumour formation. From a previous randomised controlled trial which compared large head (38 mm to 60 mm) cementless MoM THA with conventional head (28 mm) cementless MoP THA, 93 patients (96 THAs: 41 MoM (21 males, 20 females, mean age of 64 years, standard deviation (sd) 4) and 55 MoP (25 males, 30 females, mean age of 65 years, sd 5) were recruited after a mean follow-up of 50 months (36 to 64). The incidence of pseudotumours, measured using a standardised CT protocol was 22 (53.7%) after MoM THA and 12 (21.8%) after MoP THA. Women with a MoM THA were more likely to develop a pseudotumour than those with a MoP THA (15 vs 7, odds ratio (OR) = 13.4, p < 0.001). There was a similar incidence of pseudotumours in men with MoM THAs and those with MoP THAs (7 vs 5, OR = 2.1, p = 0.30). Elevated cobalt levels (≥ 5 microgram/L) were only associated with pseudotumours in women with a MoM THA. There was no difference in mean Oxford and Harris hip scores between patients with a pseudotumour and those without. Contrary to popular belief, pseudotumours occur frequently around MoP THAs. Women with a MoM THA and an elevated cobalt level are at greatest risk. In this study, pseudotumours had no effect on the functional outcome after either large head MoM or conventional MoP THA. PMID:26530649

  13. Poor mid-term survival of the low-carbide metal-on-metal Zweymüller-plus total hip arthroplasty system: a concise follow-up, at a minimum of ten years, of a previous report*.

    PubMed

    Repantis, Thomas; Vitsas, Vasilis; Korovessis, Panagiotis

    2013-03-20

    Between 1994 and 1999, 217 metal-on-metal total hip arthroplasties with a low-carbide bearing surface were performed with use of the cementless Zweymüller SL-Plus stem and the Bicon-Plus threaded cup in 194 consecutive patients. After a minimum follow-up of ten years, 181 living patients (203 hips) were available for evaluation. The revision rate after an average of twelve years was 18% (thirty-six hips in thirty-six patients were revised). The main reason for revision was aseptic loosening of one or both components. The probability of survival of the stem at fifteen years was 77% (95% confidence interval [CI], 65% to 86%). The probability of survival of the cup was 80% (95% CI, 62% to 90%). These high failure rates at mid-term follow-up led us to abandon the use of low-carbide metal-on-metal total hip arthroplasty components. PMID:23515994

  14. On the road to metallic nanoparticles by rational design: bridging the gap between atomic-level theoretical modeling and reality by total scattering experiments

    NASA Astrophysics Data System (ADS)

    Prasai, Binay; Wilson, A. R.; Wiley, B. J.; Ren, Y.; Petkov, Valeri

    2015-10-01

    The extent to which current theoretical modeling alone can reveal real-world metallic nanoparticles (NPs) at the atomic level was scrutinized and demonstrated to be insufficient and how it can be improved by using a pragmatic approach involving straightforward experiments is shown. In particular, 4 to 6 nm in size silica supported Au100-xPdx (x = 30, 46 and 58) explored for catalytic applications is characterized structurally by total scattering experiments including high-energy synchrotron X-ray diffraction (XRD) coupled to atomic pair distribution function (PDF) analysis. Atomic-level models for the NPs are built by molecular dynamics simulations based on the archetypal for current theoretical modeling Sutton-Chen (SC) method. Models are matched against independent experimental data and are demonstrated to be inaccurate unless their theoretical foundation, i.e. the SC method, is supplemented with basic yet crucial information on the length and strength of metal-to-metal bonds and, when necessary, structural disorder in the actual NPs studied. An atomic PDF-based approach for accessing such information and implementing it in theoretical modeling is put forward. For completeness, the approach is concisely demonstrated on 15 nm in size water-dispersed Au particles explored for bio-medical applications and 16 nm in size hexane-dispersed Fe48Pd52 particles explored for magnetic applications as well. It is argued that when ``tuned up'' against experiments relevant to metals and alloys confined to nanoscale dimensions, such as total scattering coupled to atomic PDF analysis, rather than by mere intuition and/or against data for the respective solids, atomic-level theoretical modeling can provide a sound understanding of the synthesis-structure-property relationships in real-world metallic NPs. Ultimately this can help advance nanoscience and technology a step closer to producing metallic NPs by rational design.The extent to which current theoretical modeling alone can

  15. On the road to metallic nanoparticles by rational design: bridging the gap between atomic-level theoretical modeling and reality by total scattering experiments.

    PubMed

    Prasai, Binay; Wilson, A R; Wiley, B J; Ren, Y; Petkov, Valeri

    2015-11-14

    The extent to which current theoretical modeling alone can reveal real-world metallic nanoparticles (NPs) at the atomic level was scrutinized and demonstrated to be insufficient and how it can be improved by using a pragmatic approach involving straightforward experiments is shown. In particular, 4 to 6 nm in size silica supported Au(100-x)Pd(x) (x = 30, 46 and 58) explored for catalytic applications is characterized structurally by total scattering experiments including high-energy synchrotron X-ray diffraction (XRD) coupled to atomic pair distribution function (PDF) analysis. Atomic-level models for the NPs are built by molecular dynamics simulations based on the archetypal for current theoretical modeling Sutton-Chen (SC) method. Models are matched against independent experimental data and are demonstrated to be inaccurate unless their theoretical foundation, i.e. the SC method, is supplemented with basic yet crucial information on the length and strength of metal-to-metal bonds and, when necessary, structural disorder in the actual NPs studied. An atomic PDF-based approach for accessing such information and implementing it in theoretical modeling is put forward. For completeness, the approach is concisely demonstrated on 15 nm in size water-dispersed Au particles explored for bio-medical applications and 16 nm in size hexane-dispersed Fe48Pd52 particles explored for magnetic applications as well. It is argued that when "tuned up" against experiments relevant to metals and alloys confined to nanoscale dimensions, such as total scattering coupled to atomic PDF analysis, rather than by mere intuition and/or against data for the respective solids, atomic-level theoretical modeling can provide a sound understanding of the synthesis-structure-property relationships in real-world metallic NPs. Ultimately this can help advance nanoscience and technology a step closer to producing metallic NPs by rational design. PMID:26463562

  16. TOTAL DISSOLVED AND BIOAVAILABLE METALS AT LAKE TEXOMA MARINAS

    EPA Science Inventory

    Dissolved metals in water and total metals in sediments have been measured at marina areas in Lake Texoma during June 1999 to October 2001, and October 2001, respectively. The metals most often found in the highest concentrations in marina water were Na and Ca, followed by Mg an...

  17. On-site analysis of heavy metal contaminated areas by means of total reflection X-ray fluorescence analysis (TXRF)

    NASA Astrophysics Data System (ADS)

    Stosnach, Hagen

    2006-11-01

    In this paper the possibilities and restriction for applying the low power TXRF spectrometer PicoTAX for the one-site analysis of heavy metal contaminated soils and sediments are evaluated. Basis for this evaluation is the Superfund Innovative Technology Evaluation (SITE) program, conducted by the U.S. Environmental Protection Protection Agency (US EPA). During a measurement campaign, performed under realistic conditions, 320 soil and sediment samples were analyzed. The task was the fast analysis of the main target elements antimony, arsenic, cadmium, chromium, copper, iron, lead, mercury, nickel, selenium, silver, vanadium, and zinc. These elements were present in wide ranging concentrations. Out of a set of seven primary and five secondary objectives the method detection limits, accuracy and precision of the TXRF measurements are discussed. In addition to the on-site measurements, the application of TXRF analysis for the analysis of soil- and sediment samples after complete microwave assisted acid digestion is reported. Recent instrument improvements have distinctly increased the quality of measurement results. A detailed description of these new developments and new measurement results are discussed

  18. Metal release and metal allergy after total hip replacement with resurfacing versus conventional hybrid prosthesis

    PubMed Central

    Gustafson, Klas; Jakobsen, Stig S; Lorenzen, Nina D; Thyssen, Jacob P; Johansen, Jeanne D; Bonefeld, Charlotte M; Stilling, Maiken; Baad-Hansen, Thomas; Søballe, Kjeld

    2014-01-01

    Background Metal-on-metal (MOM) total hip arthroplasties were reintroduced because of the problems with osteolysis and aseptic loosening related to polyethylene wear of early metal-on-polyethylene (MOP) arthroplasties. The volumetric wear rate has been greatly reduced with MOM arthroplasties; however, because of nano-size wear particles, the absolute number has been greatly increased. Thus, a source of metal ion exposure with the potential to sensitize patients is present. We hypothesized that higher amounts of wear particles result in increased release of metal ions and ultimately lead to an increased incidence of metal allergy. Methods 52 hips in 52 patients (median age 60 (51–64) years, 30 women) were randomized to either a MOM hip resurfacing system (ReCap) or a standard MOP total hip arthoplasty (Mallory Head/Exeter). Spot urine samples were collected preoperatively, postoperatively, after 3 months, and after 1, 2, and 5 years and tested with inductively coupled plasma-sector field mass spectrometry. After 5 years, hypersensitivity to metals was evaluated by patch testing and lymphocyte transformation assay. In addition, the patients answered a questionnaire about hypersensitivity. Results A statistically significant 10- to 20-fold increase in urinary levels of cobalt and chromium was observed throughout the entire follow-up in the MOM group. The prevalence of metal allergy was similar between groups. Interpretation While we observed significantly increased levels of metal ions in the urine during the entire follow-up period, no difference in prevalence of metal allergy was observed in the MOM group. However, the effect of long-term metal exposure remains uncertain. PMID:24930546

  19. Cross-shear implementation in sliding-distance-coupled finite element analysis of wear in metal-on-polyethylene total joint arthroplasty: intervertebral total disc replacement as an illustrative application.

    PubMed

    Goreham-Voss, Curtis M; Hyde, Philip J; Hall, Richard M; Fisher, John; Brown, Thomas D

    2010-06-18

    Computational simulations of wear of orthopaedic total joint replacement implants have proven to valuably complement laboratory physical simulators, for pre-clinical estimation of abrasive/adhesive wear propensity. This class of numerical formulations has primarily involved implementation of the Archard/Lancaster relationship, with local wear computed as the product of (finite element) contact stress, sliding speed, and a bearing-couple-dependent wear factor. The present study introduces an augmentation, whereby the influence of interface cross-shearing motion transverse to the prevailing molecular orientation of the polyethylene articular surface is taken into account in assigning the instantaneous local wear factor. The formulation augment is implemented within a widely utilized commercial finite element software environment (ABAQUS). Using a contemporary metal-on-polyethylene total disc replacement (ProDisc-L) as an illustrative implant, physically validated computational results are presented to document the role of cross-shearing effects in alternative laboratory consensus testing protocols. Going forward, this formulation permits systematically accounting for cross-shear effects in parametric computational wear studies of metal-on-polyethylene joint replacements, heretofore a substantial limitation of such analyses. PMID:20399432

  20. Cross-Shear Implementation in Sliding-Distance-Coupled Finite Element Analysis of Wear in Metal-on-Polyethylene Total Joint Arthroplasty: Intervertebral Total Disc Replacement as an Illustrative Application

    PubMed Central

    Goreham-Voss, Curtis M.; Hyde, Philip J.; Hall, Richard M.; Fisher, John; Brown, Thomas D.

    2010-01-01

    Computational simulations of wear of orthopaedic total joint replacement implants have proven to valuably complement laboratory physical simulators, for pre-clinical estimation of abrasive/adhesive wear propensity. This class of numerical formulations has primarily involved implementation of the Archard/Lancaster relationship, with local wear computed as the product of (finite element) contact stress, sliding speed, and a bearing-couple-dependent wear factor. The present study introduces an augmentation, whereby the influence of interface cross-shearing motion transverse to the prevailing molecular orientation of the polyethylene articular surface is taken into account in assigning the instantaneous local wear factor. The formulation augment is implemented within a widely-utilized commercial finite element software environment (ABAQUS). Using a contemporary metal-on-polyethylene total disc replacement (ProDisc-L) as an illustrative implant, physically validated computational results are presented to document the role of cross-shearing effects in alternative laboratory consensus testing protocols. Going forward, this formulation permits systematically accounting for cross-shear effects in parametric computational wear studies of metal-on-polyethylene joint replacements, heretofore a substantial limitation of such analyses. PMID:20399432

  1. Risk of revision following total hip arthroplasty: metal-on-conventional polyethylene compared with metal-on-highly cross-linked polyethylene bearing surfaces: international results from six registries.

    PubMed

    Paxton, Elizabeth; Cafri, Guy; Havelin, Leif; Stea, Susanna; Pallisó, Francesc; Graves, Stephen; Hoeffel, Daniel; Sedrakyan, Art

    2014-12-17

    The results of randomized controlled trials and systematic reviews have suggested reduced radiographic wear in highly cross-linked polyethylene compared with conventional polyethylene in primary total hip arthroplasty. However, longer-term clinical results have not been thoroughly examined, to our knowledge. The purpose of this study was to compare the risk of revision for metal-on-conventional and metal-on-highly cross-linked total hip arthroplasty bearing surfaces with use of a distributed data network of six national and regional registries (Kaiser Permanente, HealthEast, the Emilia-Romagna region in Italy, the Catalan region in Spain, Norway, and Australia). Inclusion criteria were osteoarthritis as the primary diagnosis, cementless implant fixation, and a patient age of forty-five to sixty-four years. These criteria resulted in a sample of 16,571 primary total hip arthroplasties. Multivariate meta-analysis was performed with use of linear mixed models, with survival probability as the unit of analysis. The results of a fixed-effects model suggested that there was insufficient evidence of a difference in risk of revision between bearing surfaces (hazard ratio, 1.20 [95% confidence interval, 0.80 to 1.79]; p = 0.384). Highly cross-linked polyethylene does not appear to have a reduced risk of revision in this subgroup of total hip arthroplasty patients. Arthroplasties involving highly cross-linked polyethylene do not appear to have an increased risk of revision in this subgroup of total hip arthroplasty patients. PMID:25520415

  2. Total omnidirectional reflection by sub-wavelength gradient metallic gratings

    NASA Astrophysics Data System (ADS)

    Qian, Erting; Fu, Yangyang; Xu, Yadong; Chen, Huanyang

    2016-05-01

    In this letter, we find that nearly total omnidirectional reflection could be achieved in a metallic grating structure with gradient index materials, regardless of the polarization of the incident wave. By bending the straight structure into a metallic grating ring, we design a metacage that can well shield the electromagnetic wave. All the phenomena are well demonstrated from theoretical analysis and numerical simulations.

  3. Pseudotumour formation and subsequent resolution in metal-on-metal total hip arthroplasty following revision: Instructional review and an illustrative case report with revision using a dual mobility design.

    PubMed

    Sassoon, A A; Barrack, R L

    2016-06-01

    The use of large-diameter metal-on-metal (MoM) components in total hip arthroplasty (THA) is associated with an increased risk of early failure due to adverse local tissue reaction to metal debris (ARMD) in response to the release of metal ions from the bearing couple and/or head-neck taper corrosion. The aim of this paper was to present a review of the incidence and natural history of ARMD and the forms of treatment, with a focus on the need for and extent of resection or debulking of the pseudotumour. An illustrative case report is presented of a patient with an intra-pelvic pseudotumour associated with a large diameter MoM THA, which was treated successfully with revision of the bearing surface to a dual mobility couple and retention of the well-fixed acetabular and femoral components. The pseudotumour was left in situ Resolution of the intra-pelvic mass and normalisation of metal ion levels was observed seven months post-operatively. Cite this article: Bone Joint J 2016;98-B:736-40. PMID:27235513

  4. On total disc replacement.

    PubMed

    Berg, Svante

    2011-02-01

    Low back pain consumes a large part of the community's resources dedicated to health care and sick leave. Back disorders also negatively affect the individual leading to pain suffering, decreased quality-of-life and disability. Chronic low back pain (CLBP) due to degenerative disc disease (DDD) is today often treated with fusion when conservative treatment has failed and symptoms are severe. This treatment is as successful as arthroplasty is for hip arthritis in restoring the patient's quality of life and reducing disability. Even so, there are some problems with this treatment, one of these being recurrent CLBP from an adjacent segment (ASD) after primarily successful surgery. This has led to the development of alternative surgical treatments and devices that maintain or restore mobility, in order to reduce the risk for ASD. Of these new devices, the most frequently used are the disc prostheses used in Total Disc Replacement (TDR). This thesis is based on four studies comparing total disc replacement with posterior fusion. The studies are all based on a material of 152 patients with DDD in one or two segments, aged 20-55 years that were randomly treated with either posterior fusion or TDR. The first study concerned clinical outcome and complications. Follow-up was 100% at both one and two years. It revealed that both treatment groups had a clear benefit from treatment and that patients with TDR were better in almost all outcome scores at one-year follow-up. Fusion patients continued to improve during the second year. At two-year follow-up there was a remaining difference in favour of TDR for back pain. 73% in the TDR group and 63% in the fusion group were much better or totally pain-free (n.s.), while twice as many patients in the TDR group were totally pain free (30%) compared to the fusion group (15%). Time of surgery and total time in hospital were shorter in the TDR group. There was no difference in complications and reoperations, except that seventeen of the

  5. In-vivo 6 degrees-of-freedom kinematics of metal-on-polyethylene total hip arthroplasty during gait.

    PubMed

    Tsai, Tsung-Yuan; Li, Jing-Sheng; Wang, Shaobai; Scarborough, Donna; Kwon, Young-Min

    2014-05-01

    Knowledge of accurate in-vivo 6 degree-of-freedom (6-DOF) kinematics of total hip arthroplasty (THA) during daily activities is critical for improvement of longevity of the components. Previous studies assessed in-vivo THA kinematics using skin marker-based motion analysis. However, skin markers are prone to move with respect to the underlying bones. A non-invasive dual fluoroscopic imaging system (DFIS) based tracking technique has been used to avoid skin artifacts and provide accurate 6-DOF kinematic measurement. This study aimed to quantify in-vivo 6-DOF THA kinematics during gait using DFIS. Twenty eight well-functioning THAs were evaluated during treadmill gait under DFIS surveillance. The maximum translations of the femoral head were 0.46±0.10mm and 0.45±0.10mm during the stance and swing phases (p=0.57), respectively. The range of hip flexion was from 8.7° to 47.6°, adduction from 3.0° to 12.5° and external rotation from 19.2° to 29.7°. The THA was flexed, externally rotated and adducted throughout the gait. The magnitudes of the femoral head translations were found to be within the manufacture tolerance of the components, suggesting that in-vivo hip "pistoning" during gait cycle may be minimal in well-functioning THAs. The 6-DOF kinematics could be used as the baseline knowledge for further improvement of wear-testing of hip implant, implants manufacturing and implant positioning during surgery. PMID:24704170

  6. Determination of total metal pollutants in water with optical detection

    NASA Astrophysics Data System (ADS)

    Chudy, Michal; Prokaryn, Piotr; Dybko, Artur; Wroblewski, Wojciech; Brzozka, Zbigniew

    2003-09-01

    The total concentration of heavy metal ions was measured with the use of a highly sensitive reagent (4-(2-pyridylzo)-resorcinol (PAR)). Because of PAR chelates are slightly soluble in water and their forming is not selective, the analytical procedure for Cd, Cu, Hg, Pb, Zn determination was developed to perform the analysis in an aqueous environment without the need of inconvenient and time-consuming extraction. A proposed analysis method is more useful in comparison with classical FIA analysis what is crucial during fast classification of various natural water samples. To minimize the chemicals consumption such a classification can be performed in a specially designed microsystem. The Y- shape microchannel structure with a mixing area was made by fine engraving in PMMA plate and sealed with the PDMS one. The M2+-PAR complex forming conditions were determined for each of the chosen metal ions. The solubility of formed complexes was better when a micellar environment was created by the addition of a non-ionic surfactant (Triton X100). Next the synthetic mixtures of Cd, Cu, Hg, Pb, Zn ions were prepared to obtain total molar metal ions concentration in the range from 10-6 to 10-4 M and measured after on-chip reaction. A tap water and HAC-sample (Highest Allowable Concentration, ΣMe=1,2•10-5 M) were also measured. The detection was performed in a special flow cuvette and spectra measurements were carried out using diode array spectrophotometer and CCD detector.

  7. Comparison of the risk of revision in cementless total hip arthroplasty with ceramic-on-ceramic and metal-on-polyethylene bearings

    PubMed Central

    Varnum, Claus; Pedersen, Alma B; Kjærsgaard-Andersen, Per; Overgaard, Søren

    2015-01-01

    Background and purpose Ceramic-on-ceramic (CoC) bearings were introduced in total hip arthroplasty (THA) to reduce problems related to polyethylene wear. We compared the 9-year revision risk for cementless CoC THA and for cementless metal-on-polyethylene (MoP) THA. Patients and methods In this prospective, population-based study from the Danish Hip Arthroplasty Registry, we identified all the primary cementless THAs that had been performed from 2002 through 2009 (n = 25,656). Of these, 1,773 THAs with CoC bearings and 9,323 THAs with MoP bearings were included in the study. To estimate the relative risk (RR) of revision, we used regression with the pseudo-value approach and treated death as a competing risk. Results 444 revisions were identified: 4.0% for CoC THA (71 of 1,773) and 4.0% for MoP THA (373 of 9,323). No statistically significant difference in the risk of revision for any reason was found for CoC and MoP bearings after 9 years of follow-up (adjusted RR = 1.3, 95% CI: 0.72–2.4). Revision rates due to component failure were 0.5% (n = 8) for CoC bearings and 0.1% (n = 6) for MoP bearings (p < 0.001). 6 patients with CoC bearings (0.34%) underwent revision due to ceramic fracture. Interpretation When compared to the “standard” MoP bearings, CoC THA had a 33% higher (though not statistically significantly higher) risk of revision for any reason at 9 years. PMID:25637339

  8. Alumina-on-alumina ceramic versus metal-on-highly cross-linked polyethylene bearings in total hip arthroplasty: a comparative study.

    PubMed

    Bascarevic, Zoran; Vukasinovic, Zoran; Slavkovic, Nemanja; Dulic, Borislav; Trajkovic, Goran; Bascarevic, Violeta; Timotijevic, Sladjan

    2010-12-01

    The aim of the study was to evaluate the reliability and durability of alumina-on-alumina ceramic in comparison to metal-on-highly cross-linked polyethylene (CoCr/HXLPE) bearing couples. This prospective randomised study involved 150 patients (157 hips). All patients (mean age: 54.7 years) obtained an identical fibre metal midcoat femoral stem and fibre metal-coated acetabular shell. In 78 patients (82 hips) we used alumina, while in 72 patients (75 hips) metal-polyethylene bearing couples were used. During a mean 50.4-month follow-up period (51 ± 8 alumina and 50 ± 8.9 metal-polyethylene) no statistically significant changes in clinical and radiographic parameters were noted between the two groups. There was no ceramic breakage and no need for revision surgery due to the ceramic liner. The alumina bearing couples proved to be as reliable as CoCr/HXLPE. PMID:19882338

  9. Comparison of dissolved and total metals concentrations from acute tests with saltwater organisms

    SciTech Connect

    Lussier, S.M.; Boothman, W.S.; Champlin, D.; Poucher, S.; Helmstetten, A.

    1999-05-01

    Aquatic life criteria (ALC) have traditionally been expressed for meals in terms of total-recoverable or acid-soluble concentrations. Recent US Environmental protection Agency policy recommended use of dissolved metal concentrations for setting water quality standards. Criteria derived from previous tests could be expressed in terms of dissolved metals if ratios of dissolved-to-total concentrations in those tests were consistent. Using those metals with insufficient dissolved metals data to directly derive criteria (arsenic (III), cadmium, chromium (VI), lead, nickel, selenium (IV), and zinc), the authors measured both total and dissolved metal concentrations in acute saltwater static and flow-through tests. Exposure conditions simulated those of original tests used to derive ALC. Partitioning of metals between dissolved and particulate forms was very consistent. Dissolved metal concentrations were greater than 90% of total concentrations in all tests, exceeding 95% in 10 of 13 tests. Dissolved-to-total metal ratios did not vary significantly with concentration, time, or type of test. Biological responses were consistent with historical data. Results implied that in acute saltwater toxicity tests used to establish ALC, metals were primarily dissolved. Thus criteria developed for metals based on total concentrations should be equally valid when expressed in terms of dissolved concentrations.

  10. Metal sensitivity before and after total hip arthroplasty.

    PubMed

    Deutman, R; Mulder, T J; Brian, R; Nater, J P

    1977-10-01

    Of 212 patients undergoing total hip replacement who were tested preoperatively for sensitivity to nickel, chromium, and cobalt, fourteen showed sensitivity. No sensitivity to the bone cement was recorded. Of 173 patients who had never had a metal implant before, 5.8 per cent showed a positive reaction. Two patients out of fifteen with a failed McKee-Farrar prosthesis were found to be sensitive. Of six patients who had a stable McKee-Farrar prosthesis in the other hip, none showed sensitivity to the metal. In four of sixty-six patients, sensitivity to nickel or cobalt developed after the implantation of a metal-to-plastic prosthesis. No patients were sensitized to the cement. The consequences of proved hypersensitivity in patients with metal-to-plastic prostheses, either present prior to insertion of the prosthesis or evoked by the implant material, are not known. PMID:908716

  11. Survivorship of Trabecular Metal Anchored Glenoid Total Shoulder Arthroplasties.

    PubMed

    Styron, Joseph F; Marinello, Patrick G; Peers, Sebastian; Seitz, William H

    2016-09-01

    Trabecular metal anchored glenoids (TMAGs) were developed to counter the pervasive problem of component loosening at the bone-cement interface in total shoulder arthroplasty. Increased failure rates associated with the glenoid component have been previously reported due to increased rates of glenoid failures. Our hypothesis was that in our patients, the failure rate of TMAG implants is similar to or less than reported failure rates of traditional all polyethylene glenoid components. A medical chart review of 66 consecutive patients treated with a TMAG total shoulder replacement was conducted including clinical and radiographic follow-up. Paired t test analyses were used to compare the patients' preoperative and postoperative shoulder range of motion. Patients on average had 50.2 months of clinical follow-up available. Although the radiographs of several patients demonstrated focal areas of lucency, none of the patients demonstrated evidence of glenoid loosening. Glenoid component failure was a rare occurrence, happening only once in the 66 patients (1.5%). The patient with a glenoid fracture sustained that complication 6 years after her index total shoulder replacement. She was the only patient in the series who required revision surgery. Most patients experienced significant improvements in their shoulder range of motion, improving forward flexion from 73.7 to 144.2 degrees (P<0.0001), internal rotation from L5 to T8 (P<0.0001), and external rotation 12.8 to 48.9 degrees (P<0.0001). With improved implant design and meticulous surgical technique, recent iterations of TMAG components do not produce excessive failure rates but result in significant functional improvements. PMID:27328424

  12. Determination of metallic contaminants on Ge wafers using direct- and droplet sandwich etch-total reflection X-ray fluorescence spectrometry

    NASA Astrophysics Data System (ADS)

    Hellin, D.; Bearda, T.; Zhao, C.; Raskin, G.; Mertens, P. W.; De Gendt, S.; Heyns, M. M.; Vinckier, C.

    2003-12-01

    An analysis methodology for the metallic contamination control of Ge wafer substrates has been developed and evaluated for six elements (K, Ca, Cr, Fe, Ni and Zn). Detection limits (DL) of Direct-total reflection X-ray fluorescence spectrometry (D-TXRF) analysis on Ge wafers have been determined and found to be at the E10 at/cm 2 level. The values have been found to be a factor between 1 and 3 higher than on Si wafers, exclusively caused by differences in the background intensity. Additionally, a preconcentration procedure based on the Droplet sandwich etch (DSE) method has been developed. This method relies on the transfer of the surface and subsurface contaminants from the wafer to the liquid phase by wet chemical etching. Application of the DSE method on reference Ge wafers followed by analysis of the etch liquid by TXRF resulted in recovery rates (RR) of 40%. In an optimization study, it was found that the main DSE method parameters had limited influence on the RR. However, a detection efficiency study clearly demonstrated an underestimation by the TXRF analysis. An independent analysis for Ca, Cr, Fe and Zn by GF-AAS resulted in RR varying at approximately 100%. By internal standardization with the element La for the TXRF analysis, recovery rates could be increased to the 60% level. This underestimation by TXRF may find an origin in a matrix effect caused by the Ge etch products. By application of the developed DSE-TXRF method, DL at the E9 at/cm 2 level could be realized, with values, which are at least one order of magnitude lower compared to the DL of D-TXRF on Ge wafers.

  13. Adverse local tissue reaction (ALTR) associated with corrosion products in metal-on-metal and dual modular neck total hip replacements is associated with upregulation of interferon gamma-mediated chemokine signaling.

    PubMed

    Kolatat, Kritti; Perino, Giorgio; Wilner, Gabrielle; Kaplowitz, Elianna; Ricciardi, Benjamin F; Boettner, Friedrich; Westrich, Geoffrey H; Jerabek, Seth A; Goldring, Steven R; Purdue, P Edward

    2015-10-01

    Adverse local tissue reactions (ALTR) associated with tribocorrosion following total hip arthroplasty (THA) have become a significant clinical concern in recent years. In particular, implants featuring metal-on-metal bearing surfaces and modular femoral stems have been reported to result in elevated rates of ALTR. These tribocorrosion-related tissue reactions are characterized by marked necrosis and lymphocytic infiltration, which contrasts sharply with the macrophagic and foreign body giant cell inflammation associated with polyethylene wear particle induced peri-implant osteolysis. In this study, we characterize tribocorrosion-associated ALTR at a molecular level. Gene expression profiling of peri-implant tissue around failing implants identifies upregulation of numerous inflammatory mediators in ALTR, including several interferon gamma inducible factors, most notably the chemokines MIG/CXCL9 and IP-10/CXCL10. This expression profile is distinct from that associated with polyethylene wear induced osteolysis, which is characterized by induction of markers of alternative macrophage activation, such as chitotriosidase (CHIT-1). Importantly, MIG/CXCL9 and IP-10/CXCL10 are also elevated at the protein level in the synovial fluid and, albeit more moderately, the serum, of ALTR patients, raising the possibility that these factors may serve as circulating biomarkers for the early detection of ALTR in at-risk patients. PMID:25940887

  14. Optimization of heavy metals total emission, case study: Bor (Serbia)

    NASA Astrophysics Data System (ADS)

    Ilić, Ivana; Bogdanović, Dejan; Živković, Dragana; Milošević, Novica; Todorović, Boban

    2011-07-01

    The town of Bor (Serbia) is one of the most polluted towns in southeastern Europe. The copper smelter which is situated in the centre of the town is the main pollutant, mostly because of its old technology, which leads to environmental pollution caused by higher concentrations of SO 2 and PM 10. These facts show that the word is about a very polluted region in Europe which, apart from harming human health in the region itself, poses a particular danger for wider area of southeastern Europe. Optimization of heavy metal's total emission was undertaken because years of long contamination of the soil with heavy metals of anthropogenic origin created a danger that those heavy metals may enter the food chains of animals and people, which can lead to disastrous consequences. This work represents the usage of Geographic Information System (GIS) for establishing a multifactor assessment model to quantitatively divide polluted zones and for selecting control sites in a linear programming model, combined with PROMETHEE/GAIA method, Screen View modeling system, and linear programming model. The results show that emissions at some control sites need to be cut for about 40%. In order to control the background of heavy metal pollution in Bor, the ecological environment must be improved.

  15. Correlation between the limiting pH of metal ion solubility and total metal concentration

    SciTech Connect

    Apak, R.; Hizal, J.; Ustaer, C.

    1999-03-15

    As an alternative to species distribution diagrams (pM vs pH curves in aqueous solution) drawn for a fixed total metal concentration, this work has developed simple linear models for correlating the limiting pH of metal ion solubility -- in equilibrium with the least soluble amorphous metal hydroxide solid phase -- to the total metal concentration. Thus adsorptive metal removal processes in complex systems can be better designed once the limiting pH of heavy metal solubility (i.e., pH{sup *}) in such a complex environment can be envisaged by simple linear equations. pH{sup *} vs pM{sub t} (M{sub t} = total metal concentration that can exist in aqueous solution in equilibrium with M(OH){sub 2(s)}) linear curves for uranyl-hydroxide, uranyl-carbonate-hydroxide, and mercuric-chloride-hydroxide simple and mixed-ligand systems and cupric-carbonate-hydroxide complexes in equilibrium with mixed hydroxide solid phases may enable the experimental chemist to distinguish true adsorption (e.g., onto hydrous oxide sorbents) from bulk precipitation removal of the metal and to interpret some anomalous metal fixation data -- usually attributed to pure adsorption in the literature -- with precipitation if the pM{sub t} at the studied pH is lower than that tolerated by pH{sup *} vs pM{sub t} curves. This easily predictable pH{sup *} corresponding to a given pM{sub t} may aid the design of desorptive mobilization experiments for certain metals as well as their adsorptive removal with the purpose of simulating metal adsorption and desorption cycles in real complex environments with changing groundwater pH.

  16. Serum Metal Ion Concentrations in Paediatric Patients following Total Knee Arthroplasty Using Megaprostheses

    PubMed Central

    Friesenbichler, Jörg; Sadoghi, Patrick; Maurer-Ertl, Werner; Szkandera, Joanna; Glehr, Mathias; Ogris, Kathrin; Wolf, Matthias; Weger, Christian; Leithner, Andreas

    2014-01-01

    The purpose of this study was to determine the concentrations of cobalt, chromium, and molybdenum in the serum of paediatric tumour patients after fixed hinge total knee arthroplasty. Further, these metal ion levels were compared with serum metal ion levels of patients with other orthopaedic devices such as hip and knee prostheses with metal-on-metal or metal-on-polyethylene articulation to find differences between anatomical locations, abrasion characteristics, and bearing surfaces. After an average follow-up of 108 months (range: 67 to 163) of 11 paediatric patients with fixed hinge total knee arthroplasty, the mean concentrations for Co and Cr were significantly increased while Mo was within the limits compared to the upper values from the reference laboratory. Furthermore, these serum concentrations were significantly higher compared to patients with a standard rotating hinge device (P = 0.002 and P < 0.001) and preoperative controls (P < 0.001). On the other hand, the serum levels of patients following MoM THA or rotating hinge arthroplasty using megaprostheses were higher. Therefore, periodic long-term follow-ups are recommended due to the rising concerns about systemic metal ion exposure in the literature. Upon the occurrence of adverse reactions to metal debris the revision of the fixed hinge implant should be considered. PMID:25276819

  17. Total-dose response of silicon-on-insulator (soi) metal-oxide- semiconductor field-effect transistor's (mosfet's). Master's thesis

    SciTech Connect

    Biwer, M.C.

    1988-06-01

    Total-dose response of both NMOS and PMOS FET's fabricated on SIMOX and ZMR substrates was studied. Two types of back-channel leakage currents were identified for the SIMOX devices. A back channel leakage due to MOSFET action uses the substrate bias as the gate bias. The other component is due to soft reverse characteristics of the body-drain junction. The back-channel leakage due to MOSFET action varies with the substrate bias and thus varies with irradiation due to threshold-voltage shift. The soft reverse current is a function of drain-body voltage and hence varies with substrate bias and irradiation. The threshold-voltage, I-V characteristics, and subthreshold currents of both front and back channels as a function of total dose were obtained.

  18. The characterization of total and leachable metals in foundry molding sands.

    PubMed

    Dungan, Robert S; Dees, Nikki H

    2009-01-01

    Waste molding sands from the foundry industry have been successfully used as a component in manufactured soils, but concern over metal contamination must be addressed before many states will consider this beneficial use. Since there is little data available on this topic, the purpose of this study was to characterize total and leachable metals from waste molding sands. A total elemental analysis for Ag, Al, As, B, Ba, Be, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Sb, V, and Zn was conducted on 36 clay-bonded and seven chemically bonded molding sands. Total metal concentrations in the molding sands were similar to those found in agricultural soils. The leaching of metals (i.e. Ag, As, Ba, Be, Cd, Cr, Cu, Ni, Pb, Sb, and Zn) was assessed via the toxicity characteristic leaching procedure (TCLP), synthetic precipitation leaching procedure (SPLP), and ASTM water leach test. Based on the TCLP data, none of the 43 molding sands would meet the Resource Conservation and Recovery Act (RCRA) characteristic for toxicity due to high Ag, As, Ba, Cd, Cr, and Pb. Compared to the TCLP results, the metal concentrations were generally lower in the SPLP and ASTM extracts, which is likely related to the buffering capacity of the extraction fluids. PMID:18194836

  19. Exposure assessment of metal intakes from drinking water relative to those from total diet in Japan.

    PubMed

    Ohno, Koichi; Ishikawa, Kohei; Kurosawa, Yuki; Matsui, Yoshihiko; Matsushita, Taku; Magara, Yasumoto

    2010-01-01

    Daily intakes of 17 metals (boron, aluminium, chromium, manganese, nickel, copper, zinc, arsenic, selenium, molybdenum, cadmium, antimony, lead, uranium, magnesium, calcium, and iron) via drinking water and total diet were investigated in six cities in Japan. The daily metal intakes were estimated and compared with tolerable daily intake (TDI) values proposed by the WHO or Joint FAO/WHO Expert Committee on Food Additives for toxic metals and with recommended dietary allowances (RDAs) or adequate intake (AI) values proposed for essential metals by the Japanese Ministry of Health, Labour and Welfare. Among the 13 toxic metals, mean dietary intakes of 10 (except arsenic, selenium, and molybdenum) were less than 50% of TDI, suggesting that for these 10 metals the allocation of intake to drinking water in establishing guidelines or standards could possibly be increased from the normal allocation of 10-20% of TDI. For the 13 toxic metals, the contribution of drinking water to TDI was 2% or less in all six cities. Mean dietary intakes of the essential elements magnesium, calcium, and iron were less than the RDA or AI values. Drinking water did not contribute much to essential metal intake, accounting for less than 10% of RDA or AI. PMID:21099058

  20. A hydrometallurgical process for recovering total metal values from waste monolithic ceramic capacitors.

    PubMed

    Prabaharan, G; Barik, S P; Kumar, B

    2016-06-01

    A hydrometallurgical process for recovering the total metal values from waste monolithic ceramic capacitors was investigated. The process parameters such as time, temperature, acid concentration, hydrogen peroxide concentration and other reagents (amount of zinc dust and sodium formate) were optimized. Base metals such as Ba, Ti, Sn, Cu and Ni are leached out in two stages using HCl in stage 1 and HCl with H2O2 in stage 2. More than 99% of leaching efficiency for base metals (Cu, Ni, Ba, Ti and Sn) was achieved. Precious metals such as Au and Pd are leached out using aquaregia and nitric acid was used for the leaching of Ag. Base metals (Ba, Ti, Sn, Cu and Ni) are recovered by selective precipitation using H2SO4 and NaOH solution. In case of precious metals, Au and Pd from the leach solution were precipitated out using sodium metabisulphite and sodium formate, respectively. Sodium chloride was used for the precipitation of Ag from leach solution. Overall recovery for base metals and precious metals are 95% and 92%, respectively. Based on the results of the present study, a process flow diagram was proposed for commercial application. PMID:27084106

  1. Screening for symptomatic metal sensitivity: a prospective study of 92 patients undergoing total knee arthroplasty.

    PubMed

    Niki, Yasuo; Matsumoto, Hideo; Otani, Toshiro; Yatabe, Taku; Kondo, Makoto; Yoshimine, Fumihiro; Toyama, Yoshiaki

    2005-03-01

    Metal sensitivity (MS) reactions to implant metals represent a rare but well-documented complication following total joint arthroplasty (TJA). Although 20-25% of post-TJA patients develop MS, only a few highly susceptible patients (< 1%) exhibit symptoms. Whether surgeons should perform screening for MS is currently a matter of debate. The present study investigated the clinical importance of screening for patients predisposed to symptomatic MS, and the specific metals causing symptomatic MS following total knee arthroplasty (TKA). Between 2000 and 2002, a total of 108 primary TKAs were performed on 92 patients. Preoperatively, all patients underwent modified lymphocyte stimulation test (mLST) to Ni, Co, Cr, and Fe. Of the 92 patients, 24 (26%) displayed positive preoperative responses to at least one metal. Five patients displayed implant metal-related eczema and were all mLST-positive preoperatively, suggesting that screening for symptomatic MS is clinically useful. Two of these underwent revision TKA and thereafter, eczema healed and mLST results changed from positive to negative. All mLST-positive patients were divided into three groups: Group I, patients with eczema; Group II, patients with clear history of MS; and Group III, patients neither eczema nor history of MS. When the type of sensitive metals were compared among the three groups, a significant association between presence of Cr-sensitivity and development of eczema (P < 0.05) was identified. No significant association was observed between other metals and development of eczema or history of MS. This indicates that Cr is a potential candidate metal for causing eczema in our TKA series, and Cr-sensitivity may offer a potential predictor for symptomatic MS. The present study indicates that the surgeons should undertake routine preoperative screening for MS, particularly to Cr. PMID:15369690

  2. No superiority of cemented metal-on-metal vs metal-on-polyethylene THA at 5-year follow-up.

    PubMed

    Zijlstra, Wierd P; Cheung, John; Sietsma, Maurits S; van Raay, Jos Jam; Deutman, Robert

    2009-07-01

    A randomized controlled trial was performed to compare the cemented Stanmore metal-on-metal (Biomet, Warsaw, Indiana) total hip arthroplasty (THA; 102 hips) to the cemented Stanmore metal-on-polyethylene (Biomet) THA (98 hips). The primary outcome was clinical performance. Radiological performance, serum cobalt analysis, and prosthetic survival were secondary outcome measures. At a mean follow-up of 5.6 years, 5 patients were lost to follow-up, 18 died, and 4 were revised (3 metal-on- metal, 1 metal-on-polyethylene). Harris Hip Scores improved from 48 to 90 in the metal-on-metal patients (P<.001) and from 46 to 87 in the metal-on-polyethylene patients (P<.001). Oxford Hip Scores changed from 40 to 19 in the metal-on-metal group (P<.001) and from 40 to 18 in the metal-on-polyethylene group (P<.001). For both Harris and Oxford Hip Scores, there was no significant difference between the 2 groups. Five-year survival with revision for any reason was 97% (95% CI 93%-100%) in the metal-on-metal group and 99% (95% CI 97%-100%) in the metal-on-polyethylene group. All revisions were indicated for aseptic loosening (metal-on-metal: 3 cup revisions; metal-on-polyethylene: 1 total revision). At 5-year follow-up, cemented metal-on-metal THA showed no clinical superiority over metal-on-polyethylene THA. PMID:19634856

  3. Shorter, rough trunnion surfaces are associated with higher taper wear rates than longer, smooth trunnion surfaces in a contemporary large head metal-on-metal total hip arthroplasty system.

    PubMed

    Brock, Timothy M; Sidaginamale, Raghavendra; Rushton, Steven; Nargol, Antoni V F; Bowsher, John G; Savisaar, Christina; Joyce, Tom J; Deehan, David J; Lord, James K; Langton, David J

    2015-12-01

    Taper wear at the head-neck junction is a possible cause of early failure in large head metal-on-metal (LH-MoM) hip replacements. We hypothesized that: (i) taper wear may be more pronounced in certain product designs; and (ii) an increased abductor moment arm may be protective. The tapers of 104 explanted LH-MoM hip replacements revised for adverse reaction to metal debris (ARMD) from a single manufacturer were analyzed for linear and volumetric wear using a co-ordinate measuring machine. The mated stem was a shorter 12/14, threaded trunnion (n=72) or a longer, smooth 11/13 trunnion (n=32). The abductor moment arm was calculated from pre-revision radiographs. Independent predictors of linear and volumetric wear included taper angle, stem type, and the horizontal moment arm. Tapers mated with the threaded 12/14 trunnion had significantly higher rates of volumetric wear (0.402 mm3/yr vs. 0.123 mm3/yr [t=-2.145, p=0.035]). There was a trend to larger abductor moment arms being protective (p=0.055). Design variation appears to play an important role in taper-trunnion junction failure. We recommend that surgeons bear these findings in mind when considering the use of a short, threaded trunnion with a cobalt-chromium head. PMID:26135357

  4. Enhanced Total Ionizing Dose Hardness of Deep Sub-Micron Partially Depleted Silicon-on-Insulator n-Type Metal-Oxide-Semiconductor Field Effect Transistors by Applying Larger Back-Gate Voltage Stress

    NASA Astrophysics Data System (ADS)

    Zheng, Qi-Wen; Cui, Jiang-Wei; Yu, Xue-Feng; Guo, Qi; Zhou, Hang; Ren, Di-Yuan

    2014-12-01

    The larger back-gate voltage stress is applied on 130 nm partially depleted silicon-on-insulator n-type metal-oxide-semiconductor field-effect transistors isolated by shallow trench isolation. The experimental results show that the back-gate sub-threshold hump of the device is eliminated by stress. This observed behavior is caused by the high electric field in the oxide near the bottom corner of the silicon island. The total ionizing dose hardness of devices with pre back-gate stress is enhanced by the interface states induced by stress.

  5. Retrospective cohort study of the performance of the Pinnacle metal on metal (MoM) total hip replacement: a single-centre investigation in combination with the findings of a national retrieval centre

    PubMed Central

    Langton, David John; Sidaginamale, Raghavendra Prasad; Avery, Peter; Waller, Sue; Tank, Ghanshyabhai; Lord, James; Joyce, Thomas; Cooke, Nick; Logishetty, Raj; Nargol, Antoni Viraf Francis

    2016-01-01

    Objectives To determine risk factors for revision in patients implanted with a commonly used metal on metal (MoM) hip replacement. Design Retrospective cohort study in combination with a prospective national retrieval study (Northern Retrieval Registry (NRR)). Setting Combined orthopaedic unit in combination with the NRR. Participants All patients implanted with a DePuy Pinnacle MoM hip prostheses by the 2 senior authors were invited to attend for a review which included clinical examination, blood metal ion measurements, radiographs and targeted imaging. Explanted components underwent wear analysis using validated methodology and these results were compared with those obtained from the NRR. Results 489 MoM Pinnacle hips were implanted into 434 patients (243 females and 191 males). Of these, 352 patients attended the MoM recall clinics. 64 patients had died during the study period. For the purposes of survival analysis, non-attendees were assumed to have well-functioning prostheses. The mean follow-up of the cohort as a whole was 89 months. 71 hips were revised. Prosthetic survival for the whole cohort was 83.6% (79.9–87.3) at 9 years. The majority of explanted devices exhibited signs of taper junction failure. Risk factors for revision were bilateral MoM prostheses, smaller Pinnacle liners, and implantation in 2006 and later years. A significant number of devices were found to be manufactured out of their specifications. This was confirmed with analysis of the wider data set from the NRR. Conclusions This device was found to have an unacceptably high revision rate. Bilateral prostheses, those implanted into female patients and devices implanted in later years were found to be at greater risk. A significant number of explanted components were found to be manufactured with bearing diameters outside of the manufacturer's stated tolerances. Our findings highlight the clinical importance of hitherto unrecognised variations in device production. PMID:27130159

  6. Metal oxide films on metal

    DOEpatents

    Wu, Xin D.; Tiwari, Prabhat

    1995-01-01

    A structure including a thin film of a conductive alkaline earth metal oxide selected from the group consisting of strontium ruthenium trioxide, calcium ruthenium trioxide, barium ruthenium trioxide, lanthanum-strontium cobalt oxide or mixed alkaline earth ruthenium trioxides thereof upon a thin film of a noble metal such as platinum is provided.

  7. Fate of metals in coastal sediments of a Mediterranean flood-dominated system: An approach based on total and labile fractions

    NASA Astrophysics Data System (ADS)

    Roussiez, Vincent; Ludwig, Wolfgang; Radakovitch, Olivier; Probst, Jean-Luc; Monaco, André; Charrière, Bruno; Buscail, Roselyne

    2011-05-01

    The dynamics of sediment-bound metals (Cs, Cu, Ni, Pb, Ti and Zn) were studied off the Têt River (western Gulf of Lion), a typical Mediterranean coastal river punctuated by short and violent flash-floods. Spatial and temporal sampling strategies were combined to elucidate the fate of these elements in response to both the riverine sediment input and the offshore transport of these sediments through hydrodynamics. Our results show the temporal entrapment of riverborne particles and associated metals, consecutively to a major flood event, in the nearshore sedimentary unit called prodelta. Here, deposition and resuspension mechanisms define a sedimentological cycle that could be followed completely in this study. In terms of speciation between reactive (labile) and residual fractions along the fluvio-deltaic continuum, our results show that Cu, Pb and Zn are the most labile (potentially mobile) metals in the river, in accordance with their contributions from anthropogenic sources. But in the marine surficial sediments, two main behaviours can be discriminated when compared to the riverine suspended particulate matter. While Pb and Zn depict rather a constant labile fraction, Cu is characterized by decreasing levels (up to 50% difference). In terms of environmental impact, these contrasting trends have direct repercussions for the contaminant dispersal in the coastal area. Whereas Pb and Zn conserve their enhanced levels because of their stronger affinity with fine sediments, Cu is marked by the entire loss of its anthropogenic component that is progressively transferred to the dissolved phase, likely mediated by organic ligands. We ascribe these behaviours to different post-depositional partition mechanisms with respect to oxidation of the particulate organic phase at the bottom sediment/water interface. Also, analysis of one sediment core from the prodelta indicates that these early diagenetic processes govern the chemical forms of land-derived contaminants

  8. Dissolved:total metals concentrations in marine acute toxicity test simulations

    SciTech Connect

    Lussier, S.M.; Boothman, W.S.; Champlin, D.; Poucher, S.; Helmstetter, A.

    1995-12-31

    Use of water quality criteria expressed as dissolved metal is recommended by the US EPA, Office of Water, because ``dissolved metal more closely approximates the bioavailable fraction of metal in the water column than does total recoverable metal.`` Water quality criteria (WQC) are expressed in terms of total recoverable or acid-soluble metals concentrations; in part because few toxicity tests with aquatic organisms include measurement of dissolved metals. Therefore, if WQC are to be expressed as dissolved, complete retesting or derivation of dissolved:total (D:T) metals relationships to adjust existing criteria were required. To derive D:T ratios, simulated tests were conducted using concentrations and species similar to those used to derive original criteria. Dissolved (<0.45/{micro}) and total recoverable metals were measured to determine the partitioning relationship under these experimental conditions and convert criteria to reflect dissolved metals concentrations. Simulations were conducted with arsenic (III), cadmium, chromium (VI), lead, nickel, selenium, and zinc. In all simulations, average dissolved metals comprised 93--100% of total metals measured. Dissolved:total ratios did not significantly differ for a given metal throughout each test among test type or treatment concentration. Biological results, while insufficient to derive criteria directly, were generally consistent with results of historical biological response data. These results demonstrate that, under the conditions employed, i.e, short exposure periods (2--4 days) and low particulate load typical of these tests, metals are essentially not removed from solution onto particles. This does not imply that such partitioning is representative of conditions in natural waters, but rather that in the historical acute toxicity tests used to establish water quality criteria, metals were primarily dissolved.

  9. Metal-on-Metal Hip Resurfacing Arthroplasty

    PubMed Central

    Sehatzadeh, S; Kaulback, K; Levin, L

    2012-01-01

    Background Metal-on-metal (MOM) hip resurfacing arthroplasty (HRA) is in clinical use as an appropriate alternative to total hip arthroplasty in young patients. In this technique, a metal cap is placed on the femoral head to cover the damaged surface of the bone and a metal cup is placed in the acetabulum. Objectives The primary objective of this analysis was to compare the revision rates of MOM HRA using different implants with the benchmark set by the National Institute of Clinical Excellence (NICE). The secondary objective of this analysis was to review the literature regarding adverse biological effects associated with implant material. Review Methods A literature search was performed on February 13, 2012, to identify studies published from January 1, 2009, to February 13, 2012. Results The revision rates for MOM HRA using 6 different implants were reviewed. The revision rates for MOM HRA with 3 implants met the NICE criteria, i.e., a revision rate of 10% or less at 10 years. Two implants had short-term follow-ups and MOM HRA with one of the implants failed to meet the NICE criteria. Adverse tissue reactions resulting in failure of the implants have been reported by several studies. With a better understanding of the factors that influence the wear rate of the implants, adverse tissue reactions and subsequent implant failure can be minimized. Many authors have suggested that patient selection and surgical technique affect the wear rate and the risk of tissue reactions. The biological effects of high metal ion levels in the blood and urine of patients with MOM HRA implants are not known. Studies have shown an increase in chromosomal aberrations in patients with MOM articulations, but the clinical implications and long-term consequences of this increase are still unknown. Epidemiological studies have shown that patients with MOM HRA implants did not have an overall increase in mortality or risk of cancer. There is insufficient clinical data to confirm the

  10. Development of new in situ observation system for dynamic study of lubricant molecules on metal friction surfaces by two-dimensional fast-imaging Fourier-transform infrared-attenuated total reflection spectrometer.

    PubMed

    Sasaki, Keiji; Inayoshi, Naruhiko; Tashiro, Kohji

    2008-12-01

    To observe the time-dependent two-dimensional (2D) images of spatial distribution of chemically/physically modified lubricant molecules on the metal surface during friction motion, a new in situ technique has been developed by combining the 2D fast-imaging Fourier-transform infrared-attenuated total reflection spectrometer with the temperature-controlled friction equipment containing lubricant agent. Using this new instrument, the time-dependent changes in lubricant molecules, for example, cis-trans isomerization, stress-induced molecular deformation, etc., can be detected successfully. The characteristic features of this instrument have been demonstrated in a detailed and concrete manner by demonstrating the experimental data measured for oleic acid and tricresyl phosphate. PMID:19123564

  11. Permeability of precious metals to hydrogen at 2kb total pressure and elevated temperatures.

    USGS Publications Warehouse

    Chou, I.-Ming

    1986-01-01

    Permeabilities of several commonly used precious metals to hydrogen have been measured at 2kb total pressure and between 450o and 812oC by using the double-capsule oxygen buffer technique.- from Author

  12. Removal of trabecular metal osteonecrosis intervention implant and conversion to primary total hip arthroplasty.

    PubMed

    Owens, Joshua B; Ely, Erin E; Guilliani, Nathania M Figueroa; Suarez, Juan C; Patel, Preetesh D

    2012-06-01

    Core decompression and placement of the Trabecular Metal Osteonecrosis Intervention Implant have shown to be initially successful in treating early osteonecrosis. When treatment fails, however, patients often undergo primary total hip arthroplasty (THA) requiring removal of a previously inserted trabecular metal implant. We describe a technical tip for removal of a well-ingrown trabecular metal screw. A metal-cutting trephine placed over the screw allows for removal in an efficient manner while minimizing additional dissection and bone loss during conversion to THA. PMID:22425306

  13. Metal block augmentation for bone defects of the medial tibia during primary total knee arthroplasty

    PubMed Central

    2013-01-01

    Background Stable and well-aligned placement of tibial components during primary total knee arthroplasty is challenging in patients with bone defects. Although rectangular block-shaped augmentations are widely used to reduce the shearing force between the tibial tray and bone compared with wedge-shaped augmentations, the clinical result remains unclear. This study aimed to evaluate the outcome of primary total knee arthroplasty with metal block augmentation. Methods We retrospectively reviewed the 3- to 6-year follow-up results of 33 knees that underwent total knee arthroplasty with metal block augmentation (metal-augmented group) for bone defects of the medial tibia and 132 varus knees without bone defects as the control group. All surgeries were performed using posterior-stabilized cemented prostheses in both groups. Cemented stems were routinely augmented when the metal block was used. Results There were no differences in implant survival rates (100% in metal-augmented and 99.2% in control) or knee function scores (82 points in metal-augmented and 84 points in control) between the two groups at the final follow-up examination (P = 0.60 and P = 0.09, respectively). No subsidence or loosening of the tibial tray was observed. Of 33 metal-augmented total knee arthroplasties, a nonprogressive radiolucent line beneath the metal was detected in 10 knees (30.3%), and rounding of the medial edge of the tibia was observed in 17 knees (51.5%). Conclusions The clinical results of total knee arthroplasty with metal augmentation were not inferior to those in patients without bone defects. However, radiolucent lines were observed in 30.3%. PMID:24139483

  14. Measurements of Total Hemispherical Emissivity of Several Stably Oxidized Metals and Some Refractory Oxide Coatings

    NASA Technical Reports Server (NTRS)

    Wade, William R.

    1959-01-01

    A description of the apparatus and methods used for obtaining total hemispherical emissivity is presented, and data for several stably oxidized metals are included. The metals which were tested included type 347 stainless steel, tungsten, and Haynes alloys B, C, X, and 25. No values of emissivity were obtained for tungsten or Haynes alloy B because of the nature of the oxides produced. The refractory oxide coatings tested were flame-sprayed alumina and zirconia. The results of the investigation indicate that strongly adherent, oxidized surfaces of a high stable emissivity can be produced on type 347 stainless steel for which the total hemispherical emissivity varied from 0.87 to 0.91 for temperatures from 600 F to 2,000 F. For this same temperature range, the Haynes alloys tested showed values of total hemispherical emissivity from 0.90 to 0.96 for alloy C, from 0.85 to 0.88 for alloy X, and from 0.85 to 0.89 for alloy 25. Haynes alloy B and tungsten formed nonadherent oxides at elevated temperatures and, therefore, stable emissivities were not obtained. The results obtained for the flame-sprayed ceramics (alumina and zirconia) showed considerably higher values of total emissivity than those measured for coatings applied by other methods. Emissivity values ranging from 0.69 to 0.44 for aluminum oxide and from 0.62 to 0.44 for zirconium oxide were measured for temperatures from 800 F to 2,000 F.

  15. Biomaterial Hypersensitivity: Is It Real? Supportive Evidence and Approach Considerations for Metal Allergic Patients following Total Knee Arthroplasty

    PubMed Central

    Mihalko, William M.; Grupp, Thomas M.; Manning, Blaine T.; Dennis, Douglas A.; Goodman, Stuart B.; Saleh, Khaled J.

    2015-01-01

    The prospect of biomaterial hypersensitivity developing in response to joint implant materials was first presented more than 30 years ago. Many studies have established probable causation between first-generation metal-on-metal hip implants and hypersensitivity reactions. In a limited patient population, implant failure may ultimately be related to metal hypersensitivity. The examination of hypersensitivity reactions in current-generation metal-on-metal knee implants is comparatively limited. The purpose of this study is to summarize all available literature regarding biomaterial hypersensitivity after total knee arthroplasty, elucidate overall trends about this topic in the current literature, and provide a foundation for clinical approach considerations when biomaterial hypersensitivity is suspected. PMID:25883940

  16. Biomaterial hypersensitivity: is it real? Supportive evidence and approach considerations for metal allergic patients following total knee arthroplasty.

    PubMed

    Mitchelson, Andrew J; Wilson, Craig J; Mihalko, William M; Grupp, Thomas M; Manning, Blaine T; Dennis, Douglas A; Goodman, Stuart B; Tzeng, Tony H; Vasdev, Sonia; Saleh, Khaled J

    2015-01-01

    The prospect of biomaterial hypersensitivity developing in response to joint implant materials was first presented more than 30 years ago. Many studies have established probable causation between first-generation metal-on-metal hip implants and hypersensitivity reactions. In a limited patient population, implant failure may ultimately be related to metal hypersensitivity. The examination of hypersensitivity reactions in current-generation metal-on-metal knee implants is comparatively limited. The purpose of this study is to summarize all available literature regarding biomaterial hypersensitivity after total knee arthroplasty, elucidate overall trends about this topic in the current literature, and provide a foundation for clinical approach considerations when biomaterial hypersensitivity is suspected. PMID:25883940

  17. Trace metal determination in total atmospheric deposition in rural and urban areas.

    PubMed

    Azimi, Sam; Ludwig, Alexandre; Thévenot, Daniel R; Colin, Jean-Louis

    2003-06-01

    The wet, dry and total atmospheric depositions of some metals (Al, Cd, Cr, Cu, Fe, Na, Pb and Zn) were sampled at two sites and atmospheric fallout fluxes were determined for these locations. This work, led by two different research groups, allowed to reach two main goals: to define a simple analytical procedure to secure accurate shipboard sampling and analysis of atmospheric deposition, and to assess anthropogenic impacts of heavy metals to the environment. The first step about the validation step showed that the prevalent deposition type was dry deposition which represents 40, 60 and 80% for Cd, Cu and Pb, respectively. This prevalence of dry deposition in total atmospheric fallout supported the necessity of funnel wall rinsing which contains 30, 50 and 40% of collected Cd, Cu and Pb, respectively. Moreover, the reproducibility of atmospheric deposition collection was determined. The second step was performed by comparing two sampling sites. A rural sampling site, situated in Morvan's regional park (250 km south-east of Paris), was chosen for its isolation from any local and regional contamination sources. Fluxes obtained in this area were compared with those obtained at an urban site (Créteil, suburb of Paris) allowing comparison between urban and rural areas and demonstrating the impact of anthropogenic activities on atmospheric deposition of Cr, Cu and Pb. PMID:12738217

  18. Analysis of trace metals in thin silicon nitride films by total-reflection X-ray fluorescence

    NASA Astrophysics Data System (ADS)

    Vereecke, G.; Arnauts, S.; Van Doorne, P.; Kenis, K.; Onsia, B.; Verstraeten, K.; Schaekers, M.; Van Hoeymissen, J. A. B.; Heyns, M. M.

    2001-11-01

    The validity of a matrix withdrawal method for the analysis of trace metals in silicon nitride films on silicon wafers by total-reflection X-ray fluorescence has been evaluated with samples contaminated with diluted standard solutions of eight metals (Ca, V, Cr, Fe, Ni, Cu, Ta, W). The nitride matrix was removed by a decomposition step with HF vapor at ambient conditions followed by the vaporization of the product at a temperature higher than 240°C. The recovery of added metals was determined first directly after vaporization and secondly after preconcentration by the droplet collection (DC) method. The recovery of metals after vaporization at a temperature of 300±50°C was generally close to 100%, except for Cu whose recovery was approximately 40%. The efficiency of the DC step was approximately 50% for most metals but only 10-20% for Cu and Cr. Thus for most metals the total recovery was close to 50%, which is acceptable for analytical purpose. The recovery of Cu and Cr was studied in more detail considering the influence of the thickness of the nitride film, the vaporization temperature, and the composition of the DC solution. The total recovery of Cu increased from approximately 10 to 40% by lowering the temperature of the vaporization step and using a more concentrated DC solution. The recovery of Cr by DC was markedly influenced by the thickness of the nitride film with no great benefit of using a more concentrated DC solution.

  19. Heavy metal pollution in vegetables grown in the vicinity of a multi-metal mining area in Gejiu, China: total concentrations, speciation analysis, and health risk.

    PubMed

    Li, Yanyan; Wang, Hongbin; Wang, Haijuan; Yin, Fei; Yang, Xiaoyan; Hu, Yongjun

    2014-11-01

    A field survey was conducted to investigate the present situation and health risk of arsenic (As), lead (Pb), cadmium (Cd), copper (Cu), and zinc (Zn) in soils and vegetables in a multi-metal mining area, Gejiu, China. Furthermore, three vegetables (water spinach, potato, and summer squash) containing high metal concentrations were selected to further analyze metal speciation. The results showed that the average concentrations of five metals in soil exceeded the limiting values, and their bioavailable concentrations were significantly positively correlated to the total ones. Heavy metals in the edible parts of vegetables also exceeded the corresponding standards. The leaves of pakchoi, peppermint, and coriander had a strong metal-accumulative ability and they were not suitable for planting. Except the residue forms, the main forms of metals in the edible parts of three selected vegetables were ethanol-, NaCl-, and HAc-extractable fractions for As, Pb, and Cd, respectively; however, Cu was mainly presented as NaCl-extractable and Zn as HAc-extractable fractions. A high proportion of ethanol-extractable As showed that As bioactivity and toxic effects were the highest. Although the total and bioavailable Cd were high in soil, its speciation in vegetables was mainly presented as HAc-extractable fraction, which has a relatively low bioactivity. Lead and arsenic were imposing a serious threat on the local residents via vegetable consumption. PMID:24952252

  20. Exposures to inhalable and "total" oil mist aerosol by metal machining shop workers.

    PubMed

    Wilsey, P W; Vincent, J H; Bishop, M J; Brosseau, L M; Greaves, I A

    1996-12-01

    Several recent studies have compared worker personal aerosol exposures as measured by the current method with those obtained by a new approach based on collecting the inhalable fraction, intended to represent all the particles that are capable of entering through the nose and/or mouth during breathing. The present study investigated this relationship for a metal machining facility where aerosols were generated from severely refined, nonaqueous ("straight") cutting oils used during the lathe working of metal rod stock. Workers (n = 23) wore two personal aerosol samplers simulataneously, one of the 37-mm type (for "total" aerosol exposure, E37) and the other of the Institute of Occupational Medicine (IOM) type (for inhalable aerosol exposure, EIOM). The data were analyzed by weighted least squares linear regression to determine the coefficient S in the relation EIOM = S.E37. It was found that S = 2.96 +/- 0.60. This ratio-in which exposure to inhalable aerosol was greater than to "total" aerosol-is consistent with previous observations in other industries. The relative coarsenss of the oil mist aerosol, as estimated by cascade impactor measurements, probably explains the difference between the sampling methods. The collection of large "splash" droplets, may also contribute. Future occupational aerosol standards for metalworking fluids will be based on the new, health-related criteria, and exposures will be assessed on the basis of the inhalable fraction. Results of studies like that described here will enable assessment of the impact on future workplace aerosol exposure assessments of introducing new standards. PMID:8976589

  1. Competition effects in cation binding to humic acid: Conditional affinity spectra for fixed total metal concentration conditions

    NASA Astrophysics Data System (ADS)

    David, Calin; Mongin, Sandrine; Rey-Castro, Carlos; Galceran, Josep; Companys, Encarnació; Garcés, José Luis; Salvador, José; Puy, Jaume; Cecilia, Joan; Lodeiro, Pablo; Mas, Francesc

    2010-09-01

    Information on the Pb and Cd binding to a purified Aldrich humic acid (HA) is obtained from the influence of different fixed total metal concentrations on the acid-base titrations of this ligand. NICA (Non-Ideal Competitive Adsorption) isotherm has been used for a global quantitative description of the binding, which has then been interpreted by plotting the Conditional Affinity Spectra of the H + binding at fixed total metal concentrations (CAScTM). This new physicochemical tool, here introduced, allows the interpretation of binding results in terms of distributions of proton binding energies. A large increase in the acidity of the phenolic sites as the total metal concentration increases, especially in presence of Pb, is revealed from the shift of the CAScTM towards lower affinities. The variance of the CAScTM distribution, which can be used as a direct measure of the heterogeneity, also shows a significant dependence on the total metal concentration. A discussion of the factors that influence the heterogeneity of the HA under the conditions of each experiment is provided, so that the smoothed pattern exhibited by the titration curves can be justified.

  2. Metal-backed and all-polyethylene tibial components in total knee replacement.

    PubMed

    Rodriguez, J A; Baez, N; Rasquinha, V; Ranawat, C S

    2001-11-01

    One hundred seventy-five patients with 243 consecutive primary Press Fit Condylar cruciate-substituting total knee replacements were evaluated at a mean of 5.5 years. One hundred thirteen knees had modular metal-backed tibial components and 130 had all-polyethylene tibial components. The mean knee score and functional score for the patients with unrevised components was not significantly different. The incidence of osteolysis and synovitis was higher in patients in the modular metal-backed tibia group (5%; five patients, six knees). No patients in the all-polyethylene tibia group had osteolysis or synovitis. Five revision operations were necessary: four for osteolytic defects and one for synovitis, all in patients in the modular metal-backed tibia group. All of the retrieved polyethylene inserts had evident backside wear. The best case rate of survival of the all-polyethylene tibial components was 96%+/-0.8% at 7 years and for the modular metal-backed components it was 75%+/-10% at 7 years. Metal backing and modularity were added to the Press Fit Condylar total knee replacement design to improve fixation durability. However, the superiority of the modular metal-backed implants remains in question. PMID:11716380

  3. Metal sorption on kaolinite

    SciTech Connect

    Westrich, H.R.; Brady, P.V.; Cygan, R.T.; Nagy, K.L.; Anderson, H.L.

    1997-03-01

    A key issue in performance assessment of low-level radioactive waste sites is predicting the transport and retardation of radionuclides through local soils under a variety of hydrologic and geochemical conditions. Improved transport codes should include a mechanistic model of radionuclide retardation. The authors have been investigating metal sorption (Cs{sup +}, Sr{sup 2+}, and Ba{sup 2+}) on a simple clay mineral (kaolinite) to better understand the geochemical interactions of common soil minerals with contaminated groundwaters. These studies include detailed characterizations of kaolinite surfaces, experimental adsorption measurements, surface complexation modeling, and theoretical simulations of cation sorption. The aluminol edge (010) site has been identified as the most likely site for metal sorption on kaolinite in natural solutions. Relative metal binding strengths decrease from Ba{sup 2+} to Sr{sup 2+} to Cs{sup +}, with some portion sorbed on both kaolinite edges and basal surfaces. Some Cs{sup +} also appears to be irreversibly sorbed on both sites. Molecular dynamics simulations suggest that Cs{sup +} is sorbed at aluminol (010) edge sites as an inner-sphere complex and weakly sorbed as an outer-sphere complex on (001) basal surfaces. These results provide the basis to understand and predict metal sorption onto kaolinite, and a framework to characterize sorption processes on more complex clay minerals.

  4. Skylab experiments on metals

    NASA Technical Reports Server (NTRS)

    Lundquist, C. A.

    1974-01-01

    The Skylab Materials Processing Facility is described. Eight experiments on metal processing under near-zero-gravity conditions were performed in this facility. Three of these involved metals and procedures of potential application to fabrication in space. A Multipurpose electric furnace within the Materials Processing Facility was employed to heat three ampoules of samples for each of the other five experiments. These five investigations cover diffusion versus convection rates in molten zinc, several immiscible alloy compositions, a whisker-reinforced silver-based composite, heat treating of porous silver samples, and a copper-aluminum eutectic.

  5. Mid-term results of a metal-backed glenoid component in total shoulder replacement.

    PubMed

    Castagna, A; Randelli, M; Garofalo, R; Maradei, L; Giardella, A; Borroni, M

    2010-10-01

    Total shoulder replacement is a successful procedure for degenerative or some inflammatory diseases of the shoulder. However, fixation of the glenoid seems to be the main weakness with a high rate of loosening. The results using all-polyethylene components have been better than those using metal-backed components. We describe our experience with 35 consecutive total shoulder replacements using a new metal-backed glenoid component with a mean follow-up of 75.4 months (48 to 154). Our implant differs from others because of its mechanism of fixation. It has a convex metal-backed bone interface and the main stabilising factor is a large hollow central peg. The patients were evaluated with standard radiographs and with the Constant Score, the Simple Shoulder Test and a visual analogue scale. All the scores improved and there was no loosening, no polyethylene-glenoid disassembly and no other implant-related complications. We conclude that a metal-backed glenoid component is a good option in total shoulder replacement with no worse results than of those using a cemented all-polyethylene prosthesis. PMID:20884980

  6. Effects of xenobiotics on total antioxidant capacity

    PubMed Central

    2012-01-01

    The objective of this article was to review the effects of xenobiotics on total antioxidant capacity (TAC). Measurement of TAC is appropriate for evaluation of the total antioxidant defenses of blood, cells, and different kinds of tissues and organs. TAC is reduced by alcoholism, smoking, and exposure to radiation, herbicides, carbon monoxide, carbon tetrachloride, lead, arsenic, mercury, cadmium, aluminum, and other toxic elements. The test is also an important tool in evaluating environmental and occupational exposure. PMID:23554550

  7. Size of metallic and polyethylene debris particles in failed cemented total hip replacements

    NASA Technical Reports Server (NTRS)

    Lee, J. M.; Salvati, E. A.; Betts, F.; DiCarlo, E. F.; Doty, S. B.; Bullough, P. G.

    1992-01-01

    Reports of differing failure rates of total hip prostheses made of various metals prompted us to measure the size of metallic and polyethylene particulate debris around failed cemented arthroplasties. We used an isolation method, in which metallic debris was extracted from the tissues, and a non-isolation method of routine preparation for light and electron microscopy. Specimens were taken from 30 cases in which the femoral component was of titanium alloy (10), cobalt-chrome alloy (10), or stainless steel (10). The mean size of metallic particles with the isolation method was 0.8 to 1.0 microns by 1.5 to 1.8 microns. The non-isolation method gave a significantly smaller mean size of 0.3 to 0.4 microns by 0.6 to 0.7 microns. For each technique the particle sizes of the three metals were similar. The mean size of polyethylene particles was 2 to 4 microns by 8 to 13 microns. They were larger in tissue retrieved from failed titanium-alloy implants than from cobalt-chrome and stainless-steel implants. Our results suggest that factors other than the size of the metal particles, such as the constituents of the alloy, and the amount and speed of generation of debris, may be more important in the failure of hip replacements.

  8. Feasibility of a nickel-metal hydride battery for totally implantable artificial hearts.

    PubMed

    Okamoto, E; Yoshida, T; Fujiyoshi, M; Shimanaka, M; Takeuchi, A; Mitamura, Y; Mikami, T

    1996-01-01

    An implantable rechargeable battery is one of the key technologies for totally implantable artificial hearts. The nickel-metal hydride (Ni-MH) battery is promising for its high energy density of 1.5-2.0 times that of a nickel-cadmium battery. In this study, the effects of pulsatile discharge loads on the operating time and cycle life of Ni-MH batteries at 39 degrees C were studied. Two battery cells (TH-3M, 1,200 mAh, phi 14.5 x 49 mm; Toshiba, Tokyo, Japan) in series were charge/discharge cycled at 39 degrees C using a charge current of 1CA (1,200 mA) and then were fully discharged to 1.0 V/cell under either pulsatile discharge loads, which mimicked a systole (1 A for 0.3 sec) and a diastole (0.4 A for 0.3 sec), or a non pulsatile discharge load equivalent to the average of the pulsatile loads (0.7 A). Each cycle life test was interrupted on the 482nd cycle under pulsatile load, and on the 423rd cycle under non pulsatile load, because of malfunction of each battery charger. The tests showed that the pulsatile discharge cells had significantly (p < 0.001) less operating time (74.0 +/- 7.15 min) throughout the test period (up to 482 days) compared to the cells under equivalent non pulsatile discharge loads (93.7 +/- 7.74 min). The pulsatile-discharged Ni-MH cells provide significantly less operating time than the constantly discharged cells; the Ni-MH battery has an operating time of over 78 min and a cycle life of almost 500 cycles at 39 degrees C. In conclusion, the Ni-MH battery is feasible as an implantable back-up battery for a totally implantable artificial heart system. PMID:8944901

  9. Temporal bone chondroblastoma totally invisible on MRI.

    PubMed

    Hiraumi, Harukazu; Arakawa, Yoshiki; Yamamoto, Norio; Sakamoto, Tatsunori; Ito, Juichi

    2016-08-01

    We report a case of temporal bone chondroblastoma that was totally invisible on MRI. The patient was a 64-year-old man who presented with several months history of vertigo. The CT scan with bone window setting showed destruction of the temporomandibular joint, the floor of the middle cranial fossa, and the superior semicircular canal. Calcific foci were seen within the tumor. On MR imaging, the tumor, situating mainly medial to the temporomandibular joint, showed no signal on both T1- and T2-weighted images. The tumor was not enhanced with gadolinium. In summary, the tumor was totally signal negative or "invisible" on pre- and postcontrast T1- and T2-weighted images. The tumor was resected through transpetrosal - transzygomatic approach. PMID:26743837

  10. Metal-backed versus all-polyethylene tibial components in primary total knee arthroplasty

    PubMed Central

    2011-01-01

    Background and purpose The choice of either all-polyethylene (AP) tibial components or metal-backed (MB) tibial components in total knee arthroplasty (TKA) remains controversial. We therefore performed a meta-analysis and systematic review of randomized controlled trials that have evaluated MB and AP tibial components in primary TKA. Methods The search strategy included a computerized literature search (Medline, EMBASE, Scopus, and the Cochrane Central Register of Controlled Trials) and a manual search of major orthopedic journals. A meta-analysis and systematic review of randomized or quasi-randomized trials that compared the performance of tibial components in primary TKA was performed using a fixed or random effects model. We assessed the methodological quality of studies using Detsky quality scale. Results 9 randomized controlled trials (RCTs) published between 2000 and 2009 met the inclusion quality standards for the systematic review. The mean standardized Detsky score was 14 (SD 3). We found that the frequency of radiolucent lines in the MB group was significantly higher than that in the AP group. There were no statistically significant differences between the MB and AP tibial components regarding component positioning, knee score, knee range of motion, quality of life, and postoperative complications. Interpretation Based on evidence obtained from this study, the AP tibial component was comparable with or better than the MB tibial component in TKA. However, high-quality RCTs are required to validate the results. PMID:21895503

  11. Determination of platinum group metal catalyst residues in active pharmaceutical ingredients by means of total reflection X-ray spectrometry

    NASA Astrophysics Data System (ADS)

    Marguí, Eva; Queralt, Ignasi; Hidalgo, Manuela

    2013-08-01

    The control of metal catalyst residues (i.e., platinum group metals (PGMs)) in different stages of the manufacturing processes of the active pharmaceutical ingredients (APIs) and, especially, in the final product is crucial. For API specimens, there are strict guidelines to limit the levels of metal residues based on their individual levels of safety concern. For PGMs the concentration limit has been established at 10 mg/kg in the API. Therefore great effort is currently being devoted to the development of new and simple procedures to control metals in pharmaceuticals. In the present work, an analytical methodology based on benchtop total reflection X-ray fluorescence spectrometry (TXRF) has been developed for the rapid and simple determination of some PGM catalyst impurities (Rh, Pd, Ir and Pt) in different types of API samples. An evaluation of different sample treatments (dissolution and digestion of the solid pharmaceutical samples) has been carried out and the developed methodologies have been validated according to the analytical parameters to be considered and acceptance criteria for PGM determination according to the United States Pharmacopeia (USP). Limits of quantification obtained for PGM metals were in the range of 2-4 mg/kg which are satisfactory according to current legislation. From the obtained results it is shown that the developed TXRF method can be implemented in the pharmaceutical industries to increase productivity of the laboratory; offering an interesting and complementary analytical tool to other atomic spectroscopic methods.

  12. Modeling of Total Ionizing Dose Effects in Advanced Complementary Metal-Oxide-Semiconductor Technologies

    NASA Astrophysics Data System (ADS)

    Sanchez Esqueda, Ivan

    2011-12-01

    The increased use of commercial complementary metal-oxide-semiconductor (CMOS) technologies in harsh radiation environments has resulted in a new approach to radiation effects mitigation. This approach utilizes simulation to support the design of integrated circuits (ICs) to meet targeted tolerance specifications. Modeling the deleterious impact of ionizing radiation on ICs fabricated in advanced CMOS technologies requires understanding and analyzing the basic mechanisms that result in buildup of radiation-induced defects in specific sensitive regions. Extensive experimental studies have demonstrated that the sensitive regions are shallow trench isolation (STI) oxides. Nevertheless, very little work has been done to model the physical mechanisms that result in the buildup of radiation-induced defects and the radiation response of devices fabricated in these technologies. A comprehensive study of the physical mechanisms contributing to the buildup of radiation-induced oxide trapped charges and the generation of interface traps in advanced CMOS devices is presented in this dissertation. The basic mechanisms contributing to the buildup of radiation-induced defects are explored using a physical model that utilizes kinetic equations that captures total ionizing dose (TID) and dose rate effects in silicon dioxide (SiO2). These mechanisms are formulated into analytical models that calculate oxide trapped charge density (Not) and interface trap density (Nit) in sensitive regions of deep-submicron devices. Experiments performed on field-oxide-field-effect-transistors (FOXFETs) and metal-oxide-semiconductor (MOS) capacitors permit investigating TID effects and provide a comparison for the radiation response of advanced CMOS devices. When used in conjunction with closed-form expressions for surface potential, the analytical models enable an accurate description of radiation-induced degradation of transistor electrical characteristics. In this dissertation, the incorporation

  13. The Use of Trabecular Metal Cones in Complex Primary and Revision Total Knee Arthroplasty.

    PubMed

    Brown, Nicholas M; Bell, Joshua A; Jung, Edward K; Sporer, Scott M; Paprosky, Wayne G; Levine, Brett R

    2015-09-01

    Trabecular metal cones are one option for treating osseous defects during TKA. A total of 83 consecutive TKAs utilizing cones with an average of 40 months follow-up were reviewed. There were 24 males and 59 females, with an average age of 69 years old. Four were complex primary and 79 were revision procedures. Of 83 patients, 10 (12%) required repeat revision surgery (8 infections, one periprosthetic fracture, one aseptic loosening) and overall, 37 of 83 patients (45%) experienced at least one complication. Of 73 unrevised knees, 72 (99%) demonstrated radiographic evidence of osseointegration. Despite a high complication rate in this population, trabecular metal cones represent an attractive option for managing bone loss in complex primary and revision TKA with a high rate of osseointegration. PMID:26100475

  14. Assessment of the characteristic of nutrients, total metals, and fecal coliform in Sibu Laut River, Sarawak, Malaysia

    NASA Astrophysics Data System (ADS)

    Soo, Chen-Lin; Ling, Teck-Yee; Lee, Nyanti; Apun, Kasing

    2016-03-01

    The concentrations of nutrients (nitrogen and phosphorus), total metals, and fecal coliform (FC) coupling with chlorophyll- a (chl- a), 5-day biochemical oxygen demand (BOD5) and other general environmental parameters were evaluated at the sub-surface and near-bottom water columns of 13 stations in the Sibu Laut River during low and high slack waters. The results indicated that inorganic nitrogen (mainly nitrate) was the primary form of nitrogen whereas organic phosphorus was the major form of phosphorus. The abundance of total heavy metals in Sibu Laut River and its tributaries was in the order of Pb < Cu < Zn < Cd. Fecal coliform concentration was relatively low along Sibu Laut River. The shrimp farm effluents contributed a substantial amount of chl- a, BOD5, nutrients, and FC to the receiving creek except for total metals. Nevertheless, the influence was merely noticeable in the intake creek and amended rapidly along Selang Sibu River and brought minimal effects on the Sibu Laut River. Besides, the domestic sewage effluents from villages nearby also contributed a substantial amount of pollutants.

  15. Effects of some metallic compounds on Klebsiella

    SciTech Connect

    Wong, S.H. )

    1988-05-01

    Many industrial and waste disposal practices unconsciously pollute the environment by adding excess heavy metals to it. Although reports show an inconsistency in the toxic levels of heavy metals such as zinc, nickel, cadmium, mercury and silver between microbial groups, the toxic effects of the metals on microorganisms have been well documented. Little is known of the differential effects these metals have on coliform K. pneumoniae and K. oxytoca. These bacteria are widely recognized as antibiotic resistant opportunistic pathogens ubiquitously distributed in environments. Besides, they are able to fix dinitrogen. In this study, these metals were found to affect these organisms in a variety of concentrations. Such effect could affect the total coliform count in water, dinitrogen fixation, and removable of nitrate in soil and water.

  16. Effects of some metallic compounds on Klebsiella

    SciTech Connect

    Wong, S.H.

    1988-04-01

    Many industrial and waste disposal practices unconsciously pollute the environment by adding excess heavy metals to it. Although reports show an inconsistency in the toxic levels of heavy metals such as zinc, nickel, cadmium, mercury and silvery between microbial groups, the toxic effects of the metals on microorganisms have been well documented. Little is known of the differential effects these metals have on coliform K. pneumoniae and K. oxytoca. These bacteria are widely recognized as antibiotic resistant opportunistic pathogens. Besides, they are able to fix dinitrogen. In this study, these metals were found to affect these organisms in a variety of concentrations. Such effect could affect the total coliform count in water, dinitrogen fixation, and removable of nitrate in soil and water.

  17. Metal release and corrosion effects of modular neck total hip arthroplasty

    PubMed Central

    Jakubowitz, Eike; Krachler, Michael; Thomsen, Marc; Heisel, Christian

    2009-01-01

    Modular neck implants are an attractive treatment tool in total hip replacement. Concerns remain about the mechanical stability and metal ion release caused by the modular connection. Five different implant designs were investigated in an experimental set-up. In vivo conditions were simulated and the long-term titanium release was measured. Finally, the modular connections were inspected for corrosion processes and signs of fretting. No mechanical failure or excessive corrosion could be identified for the implants tested. The titanium releases measured were extremely low compared to in vivo and in vitro studies and were not in a critical range. PMID:19219434

  18. Total on-line purchasing system (TOPS)

    SciTech Connect

    Collins, N.

    1995-11-01

    The Information Management Division (IMD) at LLNL is developing a new purchasing system for the Procurement Department. The first major development of this new system is called, {open_quotes}Total On-Line Purchasing System{close_quotes} (TOPS). TOPS will help speed up the requisitioning process by having requisitions electronically entered by requesters and electronically sent to buyers to be put on Purchase Orders. The new purchasing system will use Electronic Commerce (EC)/Electronic Data Interchange (EDI), to help increase transaction flows for shipping notices, RFQs, Quotes, Purchase Orders, and Invoices. ANSI X.12 is the EDI standard that this new EC will use.

  19. Relationship between elemental carbon, total carbon, and diesel particulate matter in several underground metal/non-metal mines.

    PubMed

    Noll, J D; Bugarski, A D; Patts, L D; Mischler, S E; McWilliams, L

    2007-02-01

    Elemental carbon (EC) is currently used as a surrogate for diesel particulate matter (DPM) in underground mines since it can be accurately measured at low concentrations and diesels are the only source of submicrometer EC in underground mines. A disadvantage of using EC as a surrogate for DPM is that the fraction of EC in DPM is a function of various engine parameters and fuel formulations, etc. In order to evaluate how EC predicts DPM in the underground mining atmosphere, measurements of total carbon (TC; representing over 80% of the DPM) and EC were taken away from potential interferences in four underground metal/non-metal mines during actual production. In a controlled atmosphere, DPM mass, TC, and EC measurements were also collected while several different types of vehicles simulated production with and without different types of control technologies. When diesel particulate filters (DPFs) were not used, both studies showed that EC could be used to predict DPM mass or TC. The variability of the data started to increase at TC concentrations below 230 microg/m3 and was high (> +/- 20%) at TC concentrations below 160 microg/m3, probably due to the problem with sampling organic carbon (OC) at these concentrations. It was also discovered that when certain DPFs were used, the relationship between DPM and EC changed at lower DPM concentrations. PMID:17333567

  20. Metallic attenuated total reflection infrared hollow fibers for robust optical transmission systems

    SciTech Connect

    Jing, Chengbin; Guo, Hong; Hu, Zhigao; Yang, Pingxiong; Chu, Junhao; Liu, Aiyun; Shi, Yiwei

    2014-07-07

    A durable metallic attenuated total reflection (ATR) hollow fiber (bore size: 1.45 mm, wall thickness: 50 μm) was designed and fabricated based on a nickel capillary tube and hexagonal germanium dioxide (GeO{sub 2}). The anomalous dispersion of the hexagonal GeO{sub 2} layer grown inside a nickel tube achieves low-loss light transmission at two peak-power wavelengths for CO{sub 2} laser devices (10.2 and 10.6 μm). An 11–28 W, 10.2 or 10.6 μm CO{sub 2} laser power was steadily delivered via a fiber elastically bent from 0° to 90° (radius: 45 cm) for over 40 min (transmission loss: 0.22 to 4.2 dB/m). Theoretically fitting the measured temperatures showed that front-end clipping caused greater thermal loading than the distributed mode absorption. The maximum external temperature of a nickel ATR fiber is much lower than that of a silica glass ATR fiber owing to their different heat dissipation abilities. The HE{sub 11} mode purity of the output beam profiles decreased from 90.3% to 44.7% as the bending angle increased from 0° to 90°. Large core sizes and wall roughnesses (scattering loss 0.04 dB/m) contributed to mode mixing and excess losses that were above the value predicted by the classical Marcatili and Schmeltzer equation (0.024–0.037 dB/m).

  1. Total fume and metal concentrations during welding in selected factories in Jeddah, Saudi Arabia.

    PubMed

    Balkhyour, Mansour Ahmed; Goknil, Mohammad Khalid

    2010-07-01

    Welding is a major industrial process used for joining metals. Occupational exposure to welding fumes is a serious occupational health problem all over the world. The degree of risk to welder's health from fumes depends on composition, concentration, and the length of exposure. The aim of this study was to investigate workers' welding fume exposure levels in some industries in Jeddah, Saudi Arabia. In each factory, the air in the breathing zone within 0.5 m from welders was sampled during 8-hour shifts. Total particulates, manganese, copper, and molybdenum concentrations of welding fumes were determined. Mean values of eight-hour average particulate concentrations measured during welding at the welders breathing zone were 6.3 mg/m(3) (Factory 1), 5.3 mg/m(3) (Factory 2), 11.3 mg/m(3) (Factory 3), 6.8 mg/m(3) (Factory 4), 4.7 mg/m(3) (Factory 5), and 3.0 mg/m(3) (Factory 6). Mean values of airborne manganese, copper, and molybdenum levels measured during welding were in the range of 0.010 mg/m(3)-0.477 mg/m(3), 0.001 mg/m(3)-0.080 mg/m(3) and 0.001 mg/m(3)-0.058 mg/m(3) respectively. Mean values of calculated equivalent exposure values were: 1.50 (Factory 1), 1.56 (Factory 2), 5.14 (Factory 3), 2.21 (Factory 4), 2.89 (Factory 5), and 1.20 (Factory 6). The welders in factories 1, 2, 3, and 4 were exposed to welding fume concentration above the SASO limit value, which may increase the risk of respiratory health problems. PMID:20717553

  2. Heavy metals and acidic components in total deposited matter in Sibenik and National Park Kornati, Croatia.

    PubMed

    Cacković, Mirjana; Kalinić, Natasa; Vadjić, Vladimira; Pehnec, Gordana

    2009-01-01

    This article presents the results of 6 years (1999-2004) of monitoring acidic components (fluoride, chloride, nitrate, sulfate) and heavy metals (lead, cadmium, thallium) in total deposited matter (TDM) in the town of Sibenik and the National Park Kornati, Croatia, in order to determine their levels, spatial and temporal variations, and possible emission source. Bulk deposition samples were collected using the Bergerhoff samplers. TDM matter was determined gravimetrically. Acidic anions were analyzed using ion chromatography. Metallic components were determined by atomic absorption spectrometry. Results show that the levels of measured pollutants were relatively low compared to those reported in other investigations. Statistical analysis indicates that the measured pollutants originate from several sources such as resuspended soil, industry, road dust, traffic, and secondary aerosols as the most important. The levels of TDM show a slightly increasing trend at all sampling sites. A significant increasing trend in the levels of nitrate and sulfate in TDM could be the consequence of increasing traffic activity and urbanization. The significant increasing trend in the ratio between nitrate and sulfate in TDM indicates that the nitrate and sulfate relative contribution to acidification is increasing. The level of heavy metals in TDM was in order of lead > thallium > cadmium at all sampling sites with slightly decreasing trend. PMID:18414927

  3. Potential Modulation on Total Internal Reflection Ellipsometry.

    PubMed

    Liu, Wei; Niu, Yu; Viana, A S; Correia, Jorge P; Jin, Gang

    2016-03-15

    Electrochemical-total internal reflection ellipsometry (EC-TIRE) has been proposed as a technique to observe the redox reactions on the electrode surface due to its high phase sensitivity to the electrolyte/electrode interface. In this paper, we mainly focus on the influence of the potential modulation on the TIRE response. The analysis suggests that both dielectric constant variation of gold and the electric double layer transformation would modulate the reflection polarization of the surface. For a nonfaradaic process, the signal of TIRE would be proportional to the potential modulation. To testify the analysis, linear sweep voltammetry and open circuit measurement have been performed. The results strongly support the system analysis. PMID:26889871

  4. The Characterization of Total and Leachable Metals in Foundry Molding Sands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Waste molding sands from the foundry industry have been successfully used as a component in manufactured soils, but concern over metal contamination must be addressed before many states will consider this beneficial use. Since there is little data available on this topic, the purpose of this study ...

  5. Radiological Stability after Revision of Infected Total Knee Arthroplasty Using Modular Metal Augments

    PubMed Central

    Lee, Kyung-Jae; Cho, Chul-Hyun; Son, Eun-Seok; Jung, Jae-Won

    2016-01-01

    Purpose To evaluate the radiological stability according to the number of modular augments after revision of infected total knee arthroplasty (TKA). Materials and Methods Between February 2006 and September 2013, 37 patients (39 knees) followed ≥2 years after revision of infected TKA using modular metal augments for bone defects were reviewed retrospectively. We divided the patients into 3 groups according to the number of augments into group A (≤2 augments, 14 knees), group B (3–4 augments, 18 knees), and group C (5≥ augments, 7 knees) and evaluated the width of radiolucent zones around the implant at the last follow-up. Results There were 3 Anderson Orthopedic Research Institute type I, 33 type II, and 3 type III bone defects. The mean number of radiolucent zones of group A was 3 and the sum of width averaged 4.4 mm. In group B, the values were 4.8 and 6.2 mm, respectively. In group C, the values were 8.1 and 12.9 mm, respectively. The differences between the three groups were statistically significant. Conclusions In revision TKA with modular metal augmentation caused by infected TKA, increased modularity can result in radiological instability. PMID:26955613

  6. Effect of total laryngectomy on esophageal motility

    SciTech Connect

    Hanks, J.B.; Fisher, S.R.; Meyers, W.C.; Christian, K.C.; Postlethwait, R.W.; Jones, R.S.

    1981-01-01

    Total laryngectomy for cancer can result in dysphagia and altered esophageal motility. Manometric changes in the upper esophageal sphincter (UES), and in proximal and distal esophageal function have been reported. However, most studies have failed to take into account radiation therapy and appropriate controls. We selected ten male patients (54.3 +/- 1.9 yr) for longitudinal manometric evaluation prior to laryngectomy then at two weeks and again six months later. No patient received preoperative radiation therapy, had a previous history of esophageal surgery, or developed a postoperative wound infection or fistula. Seven of ten patients had positive nodes and received 6,000-6,600 rads postoperative radiation therapy. Preoperatively 4 of 10 patients complained of dysphagia which did not significantly change following surgery and radiation. Two of three patients who did not complain of dysphagia preoperatively and received radiation postoperatively developed dysphagia. No patient without dysphagia preoperatively who received no radiation therapy developed symptoms. Our studies show that laryngectomy causes alterations in the UES resting and peak pressures but not in the proximal or distal esophagus, or the lower esophageal sphincter. These data also imply radiation therapy may be associated with progressive alterations in motility and symptomatology. Further study regarding the effects of radiation on esophageal motility and function are urged.

  7. Trace metal determinations by total-reflection X-ray fluorescence analysis in the open Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Schmidt, Diether; Gerwinski, Wolfgang; Radke, Ina

    1993-02-01

    The Intergovernmental Oceanographic Commission (IOC), as a major component of its programme "Global Investigation of Pollution in the Marine Environment" (GIPME), maintains a long-standing project on "Open Ocean Baseline Studies of Trace Contaminants". Initially, the Atlantic Ocean and trace metals were selected. A first cruise with the RVMeteor to the eastern parts of the south and north Atlantic Ocean was successfully organized, in March and April 1990, from Cape Town (South Africa) to Funchal (Madeira, Portugal). Thirteen scientists from laboratories in Europe and North America participated with the first author as coordinator. Four deep-water stations in the Cape Basin, Angola Basin, Cape Verde Abyssal Plain and Seine Abyssal Plain were regularly sampled for at least 36 depths. Additional samples were taken between stations. Samples were distributed to participants and a similar number of additional laboratories. As a central part of our own contribution to the project, we determined the trace heavy metals manganese, nickel, copper, zinc and lead and the lighter selenium by total-reflection X-ray fluorescence analysis. Additional methods applied, interalia, were anodic stripping voltammetry for lead and cadmium and graphite furnace atomic absorption spectrometry (GFAAS) for cadmium, using two different extraction procedures. For the TXRF, the pre-enrichment of the trace metals and the separation from the salt matrix were performed by complexation with sodium dibenzyldithiocarbamate and reverse-phase chromatography. Generally, very low levels of trace elements were found in filtered and unaltered water samples from these remote areas of the open Atlantic Ocean. Typical examples of the distributions of trace metal concentrations on depth profiles from the four deep-water stations as well as intercomparisons between the stations are presented.

  8. Method of producing adherent metal oxide coatings on metallic surfaces

    DOEpatents

    Lane, Michael H.; Varrin, Jr., Robert D.

    2001-01-01

    Provided is a process of producing an adherent synthetic corrosion product (sludge) coating on metallic surfaces. The method involves a chemical reaction between a dry solid powder mixture of at least one reactive metal oxide with orthophosphoric acid to produce a coating in which the particles are bound together and the matrix is adherent to the metallic surface.

  9. Metal-on-metal joint bearings and hematopoetic malignancy

    PubMed Central

    2012-01-01

    Abstract This is a review of the hip arthroplasty era. We concentrate on new metal bearings, surface replacements, and the lessons not learned, and we highlight recent reports on malignancies and joint implants. A low incidence of blood malignancies has been found in bone marrow taken at prosthetic surgery. The incidence is increased after replacement with knee implants that release very low systemic levels of metal ions. A carcinogenic effect of the high levels of metal ions released by large metal-on-metal implants cannot be excluded. Ongoing Swedish implant registry studies going back to 1975 can serve as a basis for evaluation of this risk. PMID:23140092

  10. Midterm Follow-Up of Metal-Backed Glenoid Components in Anatomical Total Shoulder Arthroplasties.

    PubMed

    Obermeyer, Thomas; Cagle, Paul J; Parsons, Bradford O; Flatow, Evan L

    2015-09-01

    Loosening of the glenoid remains one of the most common complications of total shoulder arthroplasty (TSA) and is the most cited reason for performing revision arthroplasty. Ingrowth metal-backed glenoid components offer the theoretical advantage of bone growth directly into the prosthesis with a single host-prosthesis interface. In the study reported here, we retrospectively reviewed the charts of patients who had TSAs performed by 2 fellowship-trained shoulder surgeons using glenoid components with porous tantalum anchors. Standard radiographs were analyzed for lucency surrounding the anchors. Before and after surgery, American Shoulder and Elbow Surgeons (ASES) scores and active forward elevation (AFE) and active external rotation (AER) measurements were recorded. Twelve shoulders (11 patients) were examined. Mean follow-up was 20 months. In all cases, radiographs showed no glenoid lucency. Mean AFE and mean AER both increased significantly (P < .01), as did postoperative ASES scores (P < .01). Porous tantalum ingrowth glenoid components show no radiographic or clinical evidence of loosening at midterm follow-up. Long-term studies are needed to determine if these midterm outcomes are maintained and provide benefit over conventional cemented polyethylene designs. PMID:26372761

  11. Prospective analysis of the incidence of metal allergy in patients listed for total replacement of the temporomandibular joint.

    PubMed

    Sidebottom, A J; Mistry, K

    2014-01-01

    We prospectively analysed the incidence of metal allergies in patients listed for total replacement of the temporomandibular joint (TMJ) and the efficacy of patch testing to prevent rejection phenomena. All patients (n=101) that required a prosthetic TMJ between March 2004 and August 2012 were tested preoperatively. A total of 39% had an allergy to one or more metals and they were given all-titanium prostheses. Following the introduction of this protocol no patients have shown signs of an allergic rejection within 6 months of operation. We suggest that all patients listed for total TMJ replacement should have patch tests for metal allergies and that all-titanium prostheses are used when allergy is detected. PMID:23850381

  12. The Inflammatory Phenotype in Failed Metal-On-Metal Hip Arthroplasty Correlates with Blood Metal Concentrations

    PubMed Central

    Paukkeri, Erja-Leena; Korhonen, Riku; Hämäläinen, Mari; Pesu, Marko; Eskelinen, Antti; Moilanen, Teemu; Moilanen, Eeva

    2016-01-01

    Introduction Hip arthroplasty is the standard treatment of a painful hip destruction. The use of modern metal-on-metal (MOM) bearing surfaces gained popularity in total hip arthroplasties during the last decade. Recently, worrisome failures due to adverse reaction to metal debris (ARMD), including pseudotumor response, have been widely reported. However, the pathogenesis of this reaction remains poorly understood. The aim of the present study was to investigate the ARMD response by flow cytometry approach. Methods Sixteen patients with a failed Articular Surface Replacement (ASR) hip prosthesis were included in the study. Samples of pseudotumor tissues collected during revision surgery were degraded by enzyme digestion and cells were typed by flow cytometry. Whole blood chromium and cobalt concentrations were analyzed with mass spectrometry before revision surgery. Results Flow cytometry analysis showed that the peri-implant pseudotumor tissue expressed two principal phenotypes, namely macrophage-dominated and T-lymphocyte-dominated response; the average portions being 54% (macrophages) and 25% (T-lymphocytes) in macrophage-dominated inflammation and 20% (macrophages) and 54% (T-lymphocytes) in T-lymphocyte-dominated response. The percentages of B-lymphocytes and granulocytes were lower in both phenotypes. Interestingly, the levels of blood chromium and cobalt were significantly higher in patients with macrophage-dominated response. Conclusions The results suggest that the adverse tissue reactions induced by MOM wear particles contain heterogeneous pathogeneses and that the metal levels are an important factor in the determination of the inflammatory phenotype. The present results support the hypothesis that higher metal levels cause cytotoxicity and tissue injury and macrophages are recruited to clear the necrotic debris. On the other hand, the adverse response developed in association with lower metal levels is T-lymphocyte-dominated and is likely to reflect

  13. Metal-on-metal: history, state of the art (2010)

    PubMed Central

    2011-01-01

    The history of metal-on-metal bearing began with K. Mc Kee. Several "episodes" have marked the history of metal-on-metal articulations, and each has contributed to a better understanding of this type of tribology. But to date the indications for this bearing are debated and are subject to reservations because of the existence of permanently elevated levels of circulating metal ions. It therefore appears that the monitoring of our patients, the documentation of our revisions and the collaboration with our industry partners as well as communicating with our biology and pathology colleagues is necessary to help us solve these problems. PMID:21234564

  14. Determination of heavy metals in macrozoobenthos from the rivers Tisza and Szamos by total reflection X-ray fluorescence spectrometry

    NASA Astrophysics Data System (ADS)

    Woelfl, S.; Mages, M.; Óvári, M.; Geller, W.

    2006-11-01

    In 2000, accidents in the Romanian mining industry in key catchment areas led to heavy metal contamination of the Hungarian rivers Tisza and Szamos resulting in substantial heavy metal loads in several sediments of the upper river basins. This enhanced metal content might have been bioaccumulated in benthic organisms during the following years. Therefore, the aim of this study was to test, whether the zoobenthic fauna showed an enhanced metal content 3 years after the industrial accident. Macrozoobenthic insect larvae (chironomids) were sampled 100 m below and above the confluent site of the rivers Tisza and Szamos during summer 2003 and for comparison purpose also in the river Maros, a tributary of the Tisza river, during 2005. In order to determine their heavy metal content, single specimens were prepared and analysed by Total Reflection X-ray Fluorescence Spectrometry (TRXF) according to the modified dry method. Fe was much lower and Mn and Zn much higher concentrated in benthos from the more contaminated Szamos river compared to the Tisza and Maros rivers. In this sense, the benthic organisms reflected very well the enhanced metal concentrations in the contaminated rivers being suitable as bioindicators of metal contamination. However, the sediment bioaccumulation factor was low at all sampling sites indicating a low bioavailability of trace metals for benthic organisms.

  15. Radiobiological speculations on therapeutic total body irradiation

    SciTech Connect

    Vriesendorp, H.M. )

    1990-01-01

    Unexpected total body irradiation (TBI) of human beings, involved in nuclear warfare or in accidents in nuclear reactors can be lethal. In the 1950s, bone marrow transplantation was discovered as a potentially life saving procedure after TBI in the dose range of 5.0 to 12.0 Gy. Since that time, deliberate or therapeutic TBI has been used to condition patients with a lethal bone marrow disorder for bone marrow replacement. The therapeutic ratio of TBI followed by bone marrow transplantation is small. Many potentially lethal complications can occur, such as acute TBI side effects, late TBI side effects or immunological complications of bone marrow transplantation such as graft versus host disease or graft rejection. The benefits of TBI and bone marrow transplantation are that they offer a chance for cure of previously lethal bone marrow disorders. The optimal parameters for TBI remain to be defined. The review discusses the current clinical and experimental animal data, as they relate to the future definition of less toxic TBI procedures with a better therapeutic ratio. Different TBI procedures are required for patients with malignant vs. non-malignant disorders or for patients with histoincompatible vs. histocompatible bone marrow donors.77 references.

  16. Intelligent Simultaneous Quantitative Online Analysis of Environmental Trace Heavy Metals with Total-Reflection X-Ray Fluorescence

    PubMed Central

    Ma, Junjie; Wang, Yeyao; Yang, Qi; Liu, Yubing; Shi, Ping

    2015-01-01

    Total-reflection X-ray fluorescence (TXRF) has achieved remarkable success with the advantages of simultaneous multi-element analysis capability, decreased background noise, no matrix effects, wide dynamic range, ease of operation, and potential of trace analysis. Simultaneous quantitative online analysis of trace heavy metals is urgently required by dynamic environmental monitoring and management, and TXRF has potential in this application domain. However, it calls for an online analysis scheme based on TXRF as well as a robust and rapid quantification method, which have not been well explored yet. Besides, spectral overlapping and background effects may lead to loss of accuracy or even faulty results during practical quantitative TXRF analysis. This paper proposes an intelligent, multi-element quantification method according to the established online TXRF analysis platform. In the intelligent quantification method, collected characteristic curves of all existing elements and a pre-estimated background curve in the whole spectrum scope are used to approximate the measured spectrum. A novel hybrid algorithm, PSO-RBFN-SA, is designed to solve the curve-fitting problem, with offline global optimization and fast online computing. Experimental results verify that simultaneous quantification of trace heavy metals, including Cr, Mn, Fe, Co, Ni, Cu and Zn, is realized on the online TXRF analysis platform, and both high measurement precision and computational efficiency are obtained. PMID:25954949

  17. Intelligent simultaneous quantitative online analysis of environmental trace heavy metals with total-reflection X-ray fluorescence.

    PubMed

    Ma, Junjie; Wang, Yeyao; Yang, Qi; Liu, Yubing; Shi, Ping

    2015-01-01

    Total-reflection X-ray fluorescence (TXRF) has achieved remarkable success with the advantages of simultaneous multi-element analysis capability, decreased background noise, no matrix effects, wide dynamic range, ease of operation, and potential of trace analysis. Simultaneous quantitative online analysis of trace heavy metals is urgently required by dynamic environmental monitoring and management, and TXRF has potential in this application domain. However, it calls for an online analysis scheme based on TXRF as well as a robust and rapid quantification method, which have not been well explored yet. Besides, spectral overlapping and background effects may lead to loss of accuracy or even faulty results during practical quantitative TXRF analysis. This paper proposes an intelligent, multi-element quantification method according to the established online TXRF analysis platform. In the intelligent quantification method, collected characteristic curves of all existing elements and a pre-estimated background curve in the whole spectrum scope are used to approximate the measured spectrum. A novel hybrid algorithm, PSO-RBFN-SA, is designed to solve the curve-fitting problem, with offline global optimization and fast online computing. Experimental results verify that simultaneous quantification of trace heavy metals, including Cr, Mn, Fe, Co, Ni, Cu and Zn, is realized on the online TXRF analysis platform, and both high measurement precision and computational efficiency are obtained. PMID:25954949

  18. Structural evolution across the insulator-metal transition in oxygen-deficient BaTiO3-δ studied using neutron total scattering and Rietveld analysis

    DOE PAGESBeta

    Jeong, I.-K.; Lee, Seunghun; Jeong, Se-Young; Won, C. J.; Hur, N.; Llobet, A.

    2011-08-29

    Oxygen-deficient BaTiO3-δ exhibits an insulator-metal transition with increasing δ. We performed neutron total scattering measurements to study structural evolution across an insulator-metal transition in BaTiO3-δ. Despite its significant impact on resistivity, slight oxygen reduction (δ=0.09) caused only a small disturbance on the local doublet splitting of Ti-O bond. This finding implies that local polarization is well preserved under marginal electric conduction. In the highly oxygen-deficient metallic state (δ=0.25), however, doublet splitting of the Ti-O bond became smeared. The smearing of the local Ti-O doublet is complemented with long-range structural analysis and demonstrates that the metallic conduction in the highly oxygen-reducedmore » BaTiO3-δ is due to the appearance of nonferroelectric cubic lattice.« less

  19. Determination of the toxicity characteristic for metals in soil: A comparison of the toxicity characteristic leaching procedure and total metal determination

    SciTech Connect

    Bass, D.A.; Taylor, J.D.

    1994-12-01

    A comparison is made of the concentrations of metals extracted from soils using the Toxicity Characteristic Leaching Procedure (TCLP) and a total determination method. This information is of interest in two ways. First, it is hoped that a relationship might be established between the amount of each metal determined after extraction by the TCLP and the amount determined using a total determination method. And second, data are also presented which indicate the general extractability of various metals in soil samples using the TCLP. This study looks specifically at inorganic elements (Sb, As, Ba, Cd, Cu, Cr, Pb, Mg, Hg, Se, Ag, Sn, and Zn) in soils from a firing range. Results show that total determination methods for metals can not generally be used for heterogeneous samples, such as soil samples from a firing range. Some correlation between a total determination method and TCLP was observed when Ba and Cd were present in the samples at lower concentrations (less than 80 mg/kg for Ba and less than 25 mg/kg for Cd); however, additional data are necessary to verify this correlation.

  20. Graphitic Tribological Layers in Metal-on-Metal Hip Replacements

    NASA Astrophysics Data System (ADS)

    Liao, Y.; Pourzal, R.; Wimmer, M. A.; Jacobs, J. J.; Fischer, A.; Marks, L. D.

    2011-12-01

    Arthritis is a leading cause of disability, and when nonoperative methods have failed, a prosthetic implant is a cost-effective and clinically successful treatment. Metal-on-metal replacements are an attractive implant technology, a lower-wear alternative to metal-on-polyethylene devices. Relatively little is known about how sliding occurs in these implants, except that proteins play a critical role and that there is a tribological layer on the metal surface. We report evidence for graphitic material in the tribological layer in metal-on-metal hip replacements retrieved from patients. As graphite is a solid lubricant, its presence helps to explain why these components exhibit low wear and suggests methods of improving their performance; simultaneously, this raises the issue of the physiological effects of graphitic wear debris.

  1. Total neutron scattering investigation of the structure of a cobalt gallium oxide spinel prepared by solvothermal oxidation of gallium metal.

    PubMed

    Playford, Helen Y; Hannon, Alex C; Tucker, Matthew G; Lees, Martin R; Walton, Richard I

    2013-11-13

    A new solvothermal synthesis route to mixed-metal gallium oxides with the spinel structure has been developed for ternary oxides of ideal composition Ga(3-x)M(x)O(4-y) (M=Co, Zn, Ni). The structure of the novel cobalt gallate produced in this manner, Ga(1.767(8))Co(0.973(8))O(3.752(8)), has been determined from total neutron scattering to be a partially defective spinel with mixed-valent cobalt (approximately 25% Co(3+) and 75% Co(2+)) and with vacancies on approximately 6% of oxygen sites. Pair distribution function (PDF) analysis reveals significant local deviations from the average cubic structure, which are attributed to the conflicting coordination preferences of the Co(2+) (potential Jahn-Teller distortion) and Ga(3+) (Ga off-centring). Reverse Monte Carlo (RMC) modelling supports this conclusion since different metal-oxygen bond-distance distributions are found for the two cations in the refined configuration. An investigation of magnetic properties shows evidence of short-range magnetic order and spin-glass-like behaviour, consistent with the structural disorder of the material. PMID:24141264

  2. Total and available heavy metal concentrations in soils of the Thriassio plain (Greece) and assessment of soil pollution indexes.

    PubMed

    Massas, Ioannis; Kalivas, Dionisios; Ehaliotis, Constantions; Gasparatos, Dionisios

    2013-08-01

    The Thriassio plain is located 25 km west of Athens city, the capital of Greece. Two major towns (Elefsina and Aspropyrgos), heavy industry plants, medium to large-scale manufacturing, logistics plants, and agriculture comprise the main land uses of the studied area. The aim of the present study was to measure the total and available concentrations of Cr, Zn, Ni, Pb, Co, Mn, Ba, Cu, and Fe in the top soils of the plain, and to asses soil contamination by these metals by using the geoaccumulation index (I geo), the enrichment factor (EF), and the availability ratio (AR) as soil pollution indexes. Soil samples were collected from 90 sampling sites, and aqua regia and DTPA extractions were carried out to determine total and available metal forms, respectively. Median total Cr, Zn, Ni, Pb, Co, Mn, Ba, Cu, and Fe concentrations were 78, 155, 81, 112, 24, 321, 834, 38, and 16 × 10(3) mg kg(-1), respectively. The available fractions showed much lower values with medians of 0.4, 5.6, 1.7, 6.9, 0.8, 5.7, 19.8, 2.1, and 2.9 mg kg(-1). Though median total metal concentrations are not considered as particularly high, the I geo and the EF values indicate moderate to heavy soil enrichment. For certain metals such as Cr, Ni, Cu, and Ba, the different distribution patterns between the EFs and the ARs suggest different origin of the total and the available metal forms. The evaluation of the EF and AR data sets for the soils of the two towns further supports the argument that the EFs can well demonstrate the long-term history of soil pollution and that the ARs can adequately portray the recent history of soil pollution. PMID:23315152

  3. Calculation of the total and total ionization cross sections for positron scattering on atomic hydrogen

    SciTech Connect

    Bray, I. ); Stelbovics, A.T. )

    1994-04-01

    The total and total ionization cross sections for positron scattering on atomic hydrogen are calculated by applying the convergent-close-coupling method to the model where positronium-formation channels are omitted. This model accurately describes the physics of the scattering whenever the positronium formation cross section is negligible, in particular, above 100 eV for this system. The total ionization cross section results in this energy region are in excellent agreement with the recent measurements of Jones [ital et] [ital al]. [J. Phys. B 26, L483 (1993)], and so lie below the earlier measurements of Spicher [Phys. Rev. Lett. 64, 1019 (1990)], and the recent calculations of Acacia [ital et] [ital al]. [Phys. Rev. Lett. (to be published)]. The total cross section is in very good agreement with the recent measurements of Zhou [ital et] [ital al]. (unpublished) down to 30 eV.

  4. Molecular Architectonic on Metal Surfaces

    NASA Astrophysics Data System (ADS)

    Barth, Johannes V.

    2007-05-01

    The engineering of highly organized systems from instructed molecular building blocks opens up new vistas for the control of matter and the exploration of nanodevice concepts. Recent investigations demonstrate that well-defined surfaces provide versatile platforms for steering and monitoring the assembly of molecular nanoarchitectures in exquisite detail. This review delineates the principles of noncovalent synthesis on metal substrates under ultrahigh vacuum conditions and briefly assesses the pertaining terminology—self-assembly, self-organization, and self-organized growth. It presents exemplary scanning-tunneling-microscopy observations, providing atomistic insight into the self-assembly of organic clusters, chains, and superlattices, and the metal-directed assembly of low-dimensional coordination architectures. This review also describes hierarchic-assembly protocols leading to intricate multilevel order. Molecular architectonic on metal surfaces represents a versatile rationale to realize structurally complex nanosystems with specific shape, composition, and functional properties, which bear promise for technological applications.

  5. Spatio-temporal variability of solid, total dissolved and labile metal: passive vs. discrete sampling evaluation in river metal monitoring.

    PubMed

    Priadi, Cindy; Bourgeault, Adeline; Ayrault, Sophie; Gourlay-Francé, Catherine; Tusseau-Vuillemin, Marie-Hélène; Bonté, Philippe; Mouchel, Jean-Marie

    2011-05-01

    In order to obtain representative dissolved and solid samples from the aquatic environment, a spectrum of sampling methods are available, each one with different advantages and drawbacks. This article evaluates the use of discrete sampling and time-integrated sampling in illustrating medium-term spatial and temporal variation. Discrete concentration index (CI) calculated as the ratio between dissolved and solid metal concentrations in grab samples are compared with time-integrated concentration index (CI) calculated from suspended particulate matter (SPM) collected in sediment traps and labile metals measured by the diffusive gel in thin films (DGT) method, collected once a month during one year at the Seine River, upstream and downstream of the Greater Paris Region. Discrete CI at Bougival was found to be significantly higher than at Triel for Co, Cu, Mn, Ni and Zn, while discrete metal partitioning at Marnay was found to be similar to Bougival and Triel. However, when using time-integrated CI, not only was Bougival CI significantly higher than Triel CI, CI at Marnay was also found to be significantly higher than CI at Triel which was not observed for discrete CI values. Since values are time-averaged, dramatic fluctuations were smoothed out and significant medium-term trends were enhanced. As a result, time-integrated concentration index (CI) was able to better illustrate urbanization impact between sites when compared to discrete CI. The impact of significant seasonal phenomenon such as winter flood, low flow and redox cycles was also, to a certain extent, visible in time-integrated CI values at the upstream site. The use of time-integrated concentration index may be useful for medium- to long-term metal studies in the aquatic environment. PMID:21468423

  6. FORMING PROTECTIVE FILMS ON METAL

    DOEpatents

    Gurinsky, D.H.; Kammerer, O.F.; Sadofsky, J.; Weeks, J.R.

    1958-12-16

    Methods are described of inhibiting the corrosion of ferrous metal by contact with heavy liquid metals such as bismuth and gallium at temperatures above 500 icient laborato C generally by bringing nltrogen and either the metal zirconium, hafnium, or titanium into reactlve contact with the ferrous metal to form a thin adherent layer of the nitride of the metal and thereafter maintaining a fractional percentage of the metal absorbed in the heavy liquid metal in contact with the ferrous metal container. The general purpose for uslng such high boiling liquid metals in ferrous contalners would be as heat transfer agents in liquid-metal-fueled nuclear reactors.

  7. Atomic oxygen effects on metals

    NASA Technical Reports Server (NTRS)

    Fromhold, Albert T.

    1987-01-01

    The effect of specimen geometry on the attack of metals by atomic oxygen is addressed. This is done by extending the coupled-currents approach in metal oxidation to spherical and cylindrical geometries. Kinetic laws are derived for the rates of oxidation of samples having these geometries. It is found that the burn-up time for spherical particles of a given diameter can be as much as a factor of 3 shorter than the time required to completely oxidize a planar sample of the same thickness.

  8. Investigation on stick phenomena in metal-on-metal hip joints after resting periods.

    PubMed

    Wimmer, M A; Nassutt, R; Sprecher, C; Loos, J; Täger, G; Fischer, A

    2006-02-01

    Insufficient understanding of tribological behaviour in total joint arthroplasty is considered as one of the reasons for prosthesis failure. Contrary to the continuous motion input profiles of hip simulators, human locomotion contains motion interruptions. These occurring resting periods can cause stick phenomena in metal-on-metal hip joints. The aim of the present study was to investigate the tribological sensitivity of all-metal bearings to motion interruptions on in vitro test specimens and retrieved implants. Friction and wear with and without resting periods were quantified. Unlike the metal-on-polyethylene joints, the static friction of metal-on-metal joints increased up to micros = 0.3 with rest, while wear appeared to be unaffected. This effect is caused by the interlocking of firmly adhered carbon layers, which were generated from the protein-containing lubricant through tribochemical reactions. Since more than 80 per cent of the retrieved implants exhibited macroscopically visible carbon layers, the increase in friction presumably also occurs under physiological conditions, which is then transferred to the bone-implant interface. These recurrent tangential stress peaks should be considered for the design features of the cup-bone interface, in particular when larger-sized implant heads are used. PMID:16669389

  9. Bioaccumulation of heavy metals in the earthworms Lumbricus rubellus and Aporrectodea caliginosa in relation to total and available metal concentrations in field soils.

    PubMed

    Hobbelen, P H F; Koolhaas, J E; van Gestel, C A M

    2006-11-01

    The aim of this study was to determine important metal pools for bioaccumulation by the earthworms Lumbricus rubellus and Aporrectodea caliginosa in soils with high binding capacity. Cd, Cu and Zn concentrations in soil, pore water and CaCl(2) extracts of soil, in leaves of the plant species Urtica dioica and in earthworms were determined at 15 field sites constituting a gradient in metal pollution. Variations in the Cu and Cd concentrations in L. rubellus and Cu concentrations in A. caliginosa were best explained by total soil concentrations, while variation in Cd concentration in A. caliginosa was best explained by pore water concentrations. Zn concentrations in L. rubellus and A. caliginosa were not significantly correlated to any determined variable. It is concluded that despite low availability, earthworms in floodplain soils contain elevated concentrations of Cu and Cd, suggesting that uptake takes place not only from the soluble metal concentrations. PMID:16530310

  10. Presence of corrosion products and hypersensitivity-associated reactions in periprosthetic tissue after aseptic loosening of total hip replacements with metal bearing surfaces.

    PubMed

    Huber, Monika; Reinisch, Georg; Trettenhahn, Günter; Zweymüller, Karl; Lintner, Felix

    2009-01-01

    Aseptic loosening of articular implants is frequently associated with tissue reactions to wear particles. Some patients, who had received metal-on-metal articulations, present early symptoms including persistent pain and implant failure. These symptoms raise the suspicion about the development of an immunological response. Furthermore, the generation of rare corrosion products in association with metallic implants has been observed. Corrosion products are known to enhance third-body wear and contribute to the loss of the implant. The purpose of this study was to investigate periprosthetic tissue containing solid corrosion products after aseptic loosening of second-generation metal-on-metal total hip replacements made of low-carbon cobalt-chromium-molybdenum alloy for the presence of immunologically determined tissue changes. Periprosthetic tissue of 11 cases containing uncommon solid deposits was investigated by light microscopy. In order to confirm the presence of corrosion products, additional methods including scanning electron microscopy (SEM) investigation, energy dispersive X-ray (EDX) and Fourier transform infrared microspectroscopy (FTIR) analysis were used. All investigated cases revealed solid chromium orthophosphate corrosion products as well as metallic wear particles to a various extent. Moreover, various intense tissue reactions characteristic of immune response were observed in all cases. The simultaneous presence of corrosion products and hypersensitivity-associated tissue reaction indicates that a relationship between corrosion development and implant-related hypersensitivity may exist. PMID:18725188

  11. Tests on Double Layer Metalization

    NASA Technical Reports Server (NTRS)

    Woo, D. S.

    1983-01-01

    28 page report describes experiments in fabrication of integrated circuits with double-layer metalization. Double-layer metalization requires much less silicon "real estate" and allows more flexibility in placement of circuit elements than does single-layer metalization.

  12. Plasmon tsunamis on metallic nanoclusters.

    PubMed

    Lucas, A A; Sunjic, M

    2012-03-14

    A model is constructed to describe inelastic scattering events accompanying electron capture by a highly charged ion flying by a metallic nanosphere. The electronic energy liberated by an electron leaving the Fermi level of the metal and dropping into a deep Rydberg state of the ion is used to increase the ion kinetic energy and, simultaneously, to excite multiple surface plasmons around the positively charged hole left behind on the metal sphere. This tsunami-like phenomenon manifests itself as periodic oscillations in the kinetic energy gain spectrum of the ion. The theory developed here extends our previous treatment (Lucas et al 2011 New J. Phys. 13 013034) of the Ar(q+)/C(60) charge exchange system. We provide an analysis of how the individual multipolar surface plasmons of the metallic sphere contribute to the formation of the oscillatory gain spectrum. Gain spectra showing characteristic, tsunami-like oscillations are simulated for Ar(15+) ions capturing one electron in distant collisions with Al and Na nanoclusters. PMID:22353847

  13. Size Distribution and Estimated Respiratory Deposition of Total Chromium, Hexavalent Chromium, Manganese, and Nickel in Gas Metal Arc Welding Fume Aerosols

    PubMed Central

    Cena, Lorenzo G.; Chisholm, William P.; Keane, Michael J.; Cumpston, Amy; Chen, Bean T.

    2016-01-01

    A laboratory study was conducted to determine the mass of total Cr, Cr(VI), Mn, and Ni in 15 size fractions for mild and stainless steel gas-metal arc welding (GMAW) fumes. Samples were collected using a nano multi orifice uniform deposition impactor (MOUDI) with polyvinyl chloride filters on each stage. The filters were analyzed by inductively coupled plasma mass spectrometry (ICP-MS) and ion chromatography. Limits of detection (LODs) and quantitation (LOQs) were experimentally calculated and percent recoveries were measured from spiked metals in solution and dry, certified welding-fume reference material. The fraction of Cr(VI) in total Cr was estimated by calculating the ratio of Cr(VI) to total Cr mass for each particle size range. Expected, regional deposition of each metal was estimated according to respiratory-deposition models. The weight percent (standard deviation) of Mn in mild steel fumes was 9.2% (6.8%). For stainless steel fumes, the weight percentages were 8.4% (5.4%) for total Cr, 12.2% (6.5%) for Mn, 2.1% (1.5%) for Ni and 0.5% (0.4%) for Cr(VI). All metals presented a fraction between 0.04 and 0.6 μm. Total Cr and Ni presented an additional fraction <0.03 μm. On average 6% of the Cr was found in the Cr(VI) valence state. There was no statistical difference between the smallest and largest mean Cr(VI) to total Cr mass ratio (p-value D 0.19), hence our analysis does not show that particle size affects the contribution of Cr(VI) to total Cr. The predicted total respiratory deposition for the metal particles was ∼25%. The sites of principal deposition were the head airways (7–10%) and the alveolar region (11–14%). Estimated Cr(VI) deposition was highest in the alveolar region (14%). PMID:26848207

  14. Airborne concentrations of metals and total dust during solid catalyst loading and unloading operations at a petroleum refinery.

    PubMed

    Lewis, Ryan C; Gaffney, Shannon H; Le, Matthew H; Unice, Ken M; Paustenbach, Dennis J

    2012-09-01

    Workers handle catalysts extensively at petroleum refineries throughout the world each year; however, little information is available regarding the airborne concentrations and plausible exposures during this type of work. In this paper, we evaluated the airborne concentrations of 15 metals and total dust generated during solid catalyst loading and unloading operations at one of the largest petroleum refineries in the world using historical industrial hygiene samples collected between 1989 and 2006. The total dust and metals, which included aluminum, cadmium, chromium, cobalt, copper, iron, lead, manganese, molybdenum, nickel, platinum, silicon, silver, vanadium, and zinc, were evaluated in relation to the handling of four different types of solid catalysts associated with three major types of catalytic processes. Consideration was given to the known components of the solid catalysts and any metals that were likely deposited onto them during use. A total of 180 analytical results were included in this analysis, representing 13 personal and 54 area samples. Of the long-term personal samples, airborne concentrations of metals ranged from <0.001 to 2.9mg/m(3), and, in all but one case, resulted in concentrations below the current U.S. Occupational Safety and Health Administration's Permissible Exposure Limits and the American Conference of Governmental Industrial Hygienists' Threshold Limit Values. The arithmetic mean total dust concentration resulting from long-term personal samples was 0.31mg/m(3). The data presented here are the most complete set of its kind in the open literature, and are useful for understanding the potential exposures during solid catalyst handling activities at this petroleum refinery and perhaps other modern refineries during the timeframe examined. PMID:22177528

  15. Internet Relaying of Total Solar Eclipse on 11 August,1999

    NASA Astrophysics Data System (ADS)

    Nagai, T.; Takahashi, N.; Okyudo, M.; Suginaka, M.; Matsumoto, N.; Team Of Live! Eclipse

    The total solar eclipse was relayed live through the Internet from Siberia, Russia, on 9 March 1997. Subsequently, the total solar eclipse was relayed from Venezuela and Guadeloupe in the Caribbean Sea in 26 February 1998, the annular solar eclipse from Malaysia on 21 August 1998, and the annular solar eclipse from Australia on 16 February 1999. The Internet was used to relay the total solar eclipse to be seen in Europe, Rumania, Turkey, and Iran. We succeeded in transmitting images from Turkey.

  16. CoCrMo Metal-on-Metal Hip Replacements

    PubMed Central

    Liao, Yifeng; Hoffman, Emily; Wimmer, Markus; Fischer, Alfons; Jacobs, Joshua; Marks, Laurence

    2012-01-01

    After the rapid growth in the use of CoCrMo metal-on-metal hip replacements since the second generation was introduced circa 1990, metal-on-metal hip replacements have experienced a sharp decline in the last two years due to biocompatibility issues related to wear and corrosion products. Despite some excellent clinical results, the release of wear and corrosion debris and the adverse response of local tissues have been of great concern. There are many unknowns regarding how CoCrMo metal bearings interact with the human body. This perspective article is intended to outline some recent progresses in understanding wear and corrosion of metal-on-metal hip replacement both in-vivo and in-vitro. The materials, mechanical deformation, corrosion, wear-assisted corrosion, and wear products will be discussed. Possible adverse health effects caused by wear products will be briefly addressed, as well as some of the many open questions such as the detailed chemistry of corrosion, tribochemical reactions and the formation of graphitic layers. Nowadays we design almost routinely for high performance materials and lubricants for automobiles; humans are at least as important. It is worth remembering that a hip implant is often the difference between walking and leading a relatively normal life, and a wheelchair. PMID:23196425

  17. CoCrMo metal-on-metal hip replacements.

    PubMed

    Liao, Yifeng; Hoffman, Emily; Wimmer, Markus; Fischer, Alfons; Jacobs, Joshua; Marks, Laurence

    2013-01-21

    After the rapid growth in the use of CoCrMo metal-on-metal hip replacements since the second generation was introduced circa 1990, metal-on-metal hip replacements have experienced a sharp decline in the last two years due to biocompatibility issues related to wear and corrosion products. Despite some excellent clinical results, the release of wear and corrosion debris and the adverse response of local tissues have been of great concern. There are many unknowns regarding how CoCrMo metal bearings interact with the human body. This perspective article is intended to outline some recent progresses in understanding wear and corrosion of metal-on-metal hip replacement both in vivo and in vitro. The materials, mechanical deformation, corrosion, wear-assisted corrosion, and wear products will be discussed. Possible adverse health effects caused by wear products will be briefly addressed, as well as some of the many open questions such as the detailed chemistry of corrosion, tribochemical reactions and the formation of graphitic layers. Nowadays we design almost routinely for high performance materials and lubricants for automobiles; humans are at least as important. It is worth remembering that a hip implant is often the difference between walking and leading a relatively normal life, and a wheelchair. PMID:23196425

  18. [Evaluation of per- and postoperative bleeding in 250 poro-metal total hip prostheses without cement].

    PubMed

    Charhon, F; Dubost, T; Terville, J P; Pastéyer, J; Roulier, J P

    1977-01-01

    Arthroplasty of the hip without cement in poro-metal (JUDET type) represents real progress. However, per-operative bleeding is greater, 48 per cent of patients losing more than 2000 ml and 25 per cent more than 3000 ml. Various factors may influence the degree of haemorrhage: the operative indication, the time of the operation and the administration of Calcium heparinate are studied. Postoperatively, overall blood loss then in relation to per-operative bleeding were evaluated. PMID:23020

  19. Taper junction failure in large-diameter metal-on-metal bearings

    PubMed Central

    Langton, D. J.; Sidaginamale, R.; Lord, J. K.; Nargol, A. V. F.; Joyce, T. J.

    2012-01-01

    Objectives An ongoing prospective study to investigate failing metal-on-metal hip prostheses was commenced at our centre in 2008. We report on the results of the analysis of the first consecutive 126 failed mated total hip prostheses from a single manufacturer. Methods Analysis was carried out using highly accurate coordinate measuring to calculate volumetric and linear rates of the articular bearing surfaces and also the surfaces of the taper junctions. The relationship between taper wear rates and a number of variables, including bearing diameter and orientation of the acetabular component, was investigated. Results The measured rates of wear and distribution of material loss from the taper surfaces appeared to show that the primary factor leading to taper failure is the increased lever arm acting on this junction in contemporary large-diameter metal-on-metal hip replacements. Conclusions Our analysis suggests that varus stems, laterally engaging taper systems and larger head diameters all contribute to taper failure. PMID:23610672

  20. A Finite-Element Study of Metal Backing and Tibial Resection Depth in a Composite Tibia Following Total Knee Arthroplasty.

    PubMed

    Tokunaga, Susumu; Rogge, Renee D; Small, Scott R; Berend, Michael E; Ritter, Merrill A

    2016-04-01

    Prosthetic alignment, patient characteristics, and implant design are all factors in long-term survival of total knee arthroplasty (TKA), yet the level at which each of these factors contribute to implant loosening has not been fully described. Prior clinical and biomechanical studies have indicated tibial overload as a cause of early TKA revision. The purpose of this study was to determine the relationship between tibial component design and bone resection on tibial loading. Finite-element analysis (FEA) was performed after simulated implantation of metal backed (MB) and all-polyethylene (AP) TKA components in 5 and 15 mm of tibial resection into a validated intact tibia model. Proximal tibial strains significantly increased between 13% and 199% when implanted with AP components (p < 0.05). Strain significantly increased between 12% and 209% in the posterior tibial compartment with increased bone resection (p < 0.05). This study indicates elevated strains in AP implanted tibias across the entirety of the proximal tibial cortex, as well as a posterior shift in tibial loading in instances of increased resection depth. These results are consistent with trends observed in prior biomechanical studies and may associate the documented device history of tibial collapse in AP components with increased bone strain and overload beneath the prosthesis. PMID:26810930

  1. Total and labile metals in surface sediments of the tropical river-estuary system of Marabasco (Pacific coast of Mexico): Influence of an iron mine.

    PubMed

    Marmolejo-Rodríguez, Ana Judith; Prego, Ricardo; Meyer-Willerer, Alejandro; Shumilin, Evgueni; Cobelo-García, Antonio

    2007-01-01

    Marabasco is a tropical river-estuary system comprising the Marabasco river and the Barra de Navidad Lagoon. The river is impacted by the Peña Colorada iron mine, which produces 3.5 million tons of pellets per year. Thirteen surface sediment samples were collected in May 2005 (dry season) in order to establish background levels of Al, Cd, Co, Cu, Fe, Ni, Pb, and Zn in the system and to ascertain the potential mobility of metals in the sediments. Analyses were carried out in the fraction finer than 63 microm, and labile metals extracted according the BCR procedure. Certified reference materials were used for validation of methods. Total concentrations of Cd, Co, Cu, Ni, Pb, and Zn were in the range of 0.05-0.34, 6-95, 0.7-31, 9-26, 2-18, and 53-179 mgkg(-1), respectively; Al and Fe ranges of 24-127, and 26-69 mgg(-1) correspondingly. Cadmium was found to be significantly labile in the sediments (20-100%), followed by Co (0-35%), Ni (3-16%) and Zn (0-25%), whereas the labile fraction for Cu, Fe and Pb was almost negligible (<4%). According with the total metal concentrations, background levels and normalised enrichment factors (NEF) of the metals studied, the impact of the Peña Colorada iron mine on the Marabasco system is lower than expected when compared with other similar World systems influenced by mining activities. PMID:17997460

  2. Cancer incidence and cause-specific mortality in patients with metal-on-metal hip replacements in Finland

    PubMed Central

    2014-01-01

    Background and purpose Metal-on-metal hip implants have been widely used, especially in the USA, Australia, England and Wales, and Finland. We assessed risk of death and updated data on the risk of cancer related to metal-on-metal hip replacements. Patients and methods A cohort of 10,728 metal-on-metal hip replacement patients and a reference cohort of 18,235 conventional total hip replacement patients were extracted from the Finnish Arthroplasty Register for the years 2001–2010. Data on incident cancer cases and causes of death until 2011 were obtained from the Finnish Cancer Registry and Statistics Finland. The relative risk of cancer and death were expressed as standardized incidence ratio (SIR) and standardized mortality ratio (SMR). SIR/SIR ratios and SMR/SMR ratios, and Poisson regression were used to compare the cancer risk and the risk of death between cohorts. Results The overall risk of cancer in the metal-on-metal cohort was not higher than that in the non-metal-on-metal cohort (RR = 0.91, 95% CI: 0.82–1.02). The risk of soft-tissue sarcoma and basalioma in the metal-on-metal cohort was higher than in the non-metal-on-metal cohort (SIR/SIR ratio = 2.6, CI: 1.02–6.4 for soft-tissue sarcoma; SIR/SIR ratio = 1.3, CI: 1.1–1.5 for basalioma). The overall risk of death in the metal-on-metal cohort was less than that in the non-metal-on-metal cohort (RR = 0.78, CI: 0.69–0.88). Interpretation The overall risk of cancer or risk of death because of cancer is not increased after metal-on-metal hip replacement. The well-patient effect and selection bias contribute substantially to the findings concerning mortality. Arthrocobaltism does not increase mortality in patients with metal-on-metal hip implants in the short term. However, metal-on-metal hip implants should not be considered safe until data with longer follow-up time are available. PMID:24397743

  3. On the inflammatory response in metal-on-metal implants

    PubMed Central

    2014-01-01

    Background Metal-on-metal implants are a special form of hip endoprostheses that despite many advantages can entail serious complications due to release of wear particles from the implanted material. Metal wear particles presumably activate local host defence mechanisms, which causes a persistent inflammatory response with destruction of bone followed by a loosening of the implant. To better characterize this inflammatory response and to link inflammation to bone degradation, the local generation of proinflammatory and osteoclast-inducing cytokines was analysed, as was systemic T cell activation. Methods By quantitative RT-PCR, gene expression of cytokines and markers for T lymphocytes, monocytes/macrophages and osteoclasts, respectively, was analysed in tissue samples obtained intraoperatively during exchange surgery of the loosened implant. Peripheral T cells were characterized by cytofluorometry before surgery and 7 to 10 days thereafter. Results At sites of osteolysis, gene expression of cathepsin K, CD14 and CD3 was seen, indicating the generation of osteoclasts, and the presence of monocytes and of T cells, respectively. Also cytokines were highly expressed, including CXCL8, IL-1ß, CXCL2, MRP-14 and CXCL-10. The latter suggest T cell activation, a notion that could be confirmed by detecting a small, though conspicuous population of activated CD4+ cells in the peripheral blood T cells prior to surgery. Conclusion Our data support the concept that metallosis is the result of a local inflammatory response, which according to histomorphology and the composition of the cellular infiltrate classifies as an acute phase of a chronic inflammatory disease. The proinflammatory environment, particularly the generation of the osteoclast-inducing cytokines CXCL8 and IL1-ß, promotes bone resorption. Loss of bone results in implant loosening, which then causes the major symptoms of metallosis, pain and reduced range of motion. PMID:24650243

  4. Zirconia phase transformation, metal transfer, and surface roughness in retrieved ceramic composite femoral heads in total hip arthroplasty.

    PubMed

    Elpers, Marcella; Nam, Denis; Boydston-White, Susie; Ast, Michael P; Wright, Timothy M; Padgett, Douglas E

    2014-11-01

    Ceramic femoral heads have had promising results as a bearing surface in total hip arthroplasty. Our objective was to evaluate a series of retrieved alumina-zirconia composite ceramic femoral heads for evidence of the tetragonal to monoclinic zirconia phase transformation, metal transfer and articular surface roughness. Raman spectra showed evidence of the zirconia phase transformation in all retrieved specimens, with distinct monoclinic peaks at 183, 335, 383, and 479 cm(-1). All components displayed metal transfer. An increase in the zirconia phase transformation was seen with increasing time in vivo. No correlation between extent of zirconia phase transformation and the surface roughness was found. These short-term results suggest that the use of an alumina-zirconia composite ceramic is a viable option for femoral heads in THA. PMID:25212282

  5. Effects of micronutrients on metal toxicity.

    PubMed Central

    Peraza, M A; Ayala-Fierro, F; Barber, D S; Casarez, E; Rael, L T

    1998-01-01

    There is growing evidence that micronutrient intake has a significant effect on the toxicity and carcinogenesis caused by various chemicals. This paper examines the effect of micronutrient status on the toxicity of four nonessential metals: cadmium, lead, mercury, and arsenic. Unfortunately, few studies have directly examined the effect of dietary deficiency or supplementation on metal toxicity. More commonly, the effect of dietary alteration must be deduced from the results of mechanistic studies. We have chosen to separate the effect of micronutrients on toxic metals into three classes: interaction between essential micronutrients and toxic metals during uptake, binding, and excretion; influence of micronutrients on the metabolism of toxic metals; and effect of micronutrients on secondary toxic effects of metals. Based on data from mechanistic studies, the ability of micronutrients to modulate the toxicity of metals is indisputable. Micronutrients interact with toxic metals at several points in the body: absorption and excretion of toxic metals; transport of metals in the body; binding to target proteins; metabolism and sequestration of toxic metals; and finally, in secondary mechanisms of toxicity such as oxidative stress. Therefore, people eating a diet deficient in micronutrients will be predisposed to toxicity from nonessential metals. PMID:9539014

  6. Photochemistry on rough metal surfaces

    SciTech Connect

    Goncher, G.M.; Parsons, C.A.; Harris, C.B.

    1984-09-13

    The general question of laser-induced photochemistry on metal surfaces is addressed. Specifically, the authors have studied resonant photodecomposition of a variety of aromatic molecules on roughened silver surfaces in ultrahigh vacuum. A continuous ion laser source at a number of different wavelengths in the region 350-410 nm was used to produce graphitic carbon on the surface which was monitored by Raman spectroscopy at the 1580-cm/sup -1/ band of surface carbon. Laser power-dependence studies of fragmentation rate for several molecules at 406.7nm indicate that the initial absorption step is a two-photon process. Energetic considerations imply that photochemistry for other molecules studied is also due to multiphoton absorption, except for benzaldehyde fragmentation at 350.7-nm excitation, where the photodecomposition rate is linear. Distance-dependence studies of photofragmentation rates by use of an inert spacer layer to separatte the molecule undergoing photochemistry from the surface indicate that energy transfer to the metal surface is important in determining the reaction rate. Decomposition mechanism has not been fully evaluated.

  7. High total dose effects on CMOS/SOI technology

    SciTech Connect

    Flament, O.; Dupont-Nivet, E.; Leray, J.L.; Pere, J.F.; Delagnes, E. ); Auberton-Herve, A.J.; Giffard, B. ); Borel, G.; Ouisse, T. )

    1992-06-01

    This paper reports that, CMOS silicon on insulator technology has shown its ability to process hardened components which remain functional after irradiation with a total dose of several tens of Megarads. New tests on elementary transistors and 29101 microprocessor have been made at doses up to 100 Mrad (SiO{sub 2}) and above. Results of irradiation at these total doses are presented for different biases, together with the post-irradiation behavior of the components. All the observations show that new parameters must be taken into account for hardness insurance at a high level of total dose.

  8. Totem Results on Elastic Scattering and Total Cross-Section

    NASA Astrophysics Data System (ADS)

    Kašpar, Jan

    2015-06-01

    TOTEM is an LHC experiment dedicated to forward hadronic physics. In this contribution, an update on two main parts of its physics programme is given: proton-proton elastic scattering and total cross-section.

  9. Winter-time size distribution and source apportionment of total suspended particulate matter and associated metals in Delhi

    NASA Astrophysics Data System (ADS)

    Srivastava, Arun; Gupta, Sandeep; Jain, V. K.

    2009-03-01

    A study of the winter time size distribution and source apportionment of total suspended particulate matter (TSPM) and associated heavy metal concentrations have been carried out for the city of Delhi. This study is important from the point of view of implementation of compressed natural gas (CNG) as alternate of diesel fuel in the public transport system in 2001 to reduce the pollution level. TSPM were collected using a five-stage cascade impactor at six sites in the winters of 2005-06. The results of size distribution indicate that a major portion (~ 40%) of TSPM concentration is in the form of PM0.7 (< 0.7 μm). Similar trends were observed with most of the heavy metals associated with various size fractions of TSPM. A very good correlation between coarse and fine size fraction of TSPM was observed. It was also observed that the metals associated with coarse particles have more chances of correlation with other metals; rather they are associated with fine particles. Source apportionment was carried out separately in coarse and fine size modes of TSPM by Chemical Mass Balance Receptor Model (CMB8) as well as by Principle Component Analysis (PCA) of SPSS. Source apportionment by PCA reveals that there are two major sources (possibly vehicular and crustal re-suspension) in both coarse and fine size fractions. Results obtained by CMB8 show the dominance of vehicular pollutants and crustal dust in fine and coarse size mode respectively. Noticeably the dominance of vehicular pollutants are now confined to fine size only whilst during pre CNG era it dominated both coarse and fine size mode. An increase of 42.5, 44.4, 48.2, 38.6 and 38.9% in the concentrations of TSPM, PM10.9, coarse particles, fine particles and lead respectively was observed during pre (2001) to post CNG (2005-06) period.

  10. Theoretical differential Raman scattering cross-sections of totally-symmetric vibrational modes of free pyridine and pyridine-metal cluster complexes

    NASA Astrophysics Data System (ADS)

    Wu, D. Y.; Hayashi, M.; Lin, S. H.; Tian, Z. Q.

    2004-01-01

    The differential Raman scattering cross-sections of totally-symmetric vibrational modes for pyridine and pyridine-metal clusters have been calculated by using ab initio and density functional methods. The results are compared with experimental data and a good agreement is obtained. In particular, we can theoretically reproduce the significant changes in the relative Raman intensities of the ν12 mode in pyridine-metal cluster complexes. We focus on two mechanisms for these Raman intensities changes: (1) the chemical interaction between the pyridine and the metal clusters; and (2) the charge transfer mechanism. For the pyridine-silver cluster complexes, we find that due to the weak bonding, the chemical interaction does not influence the relative intensities of the Raman peaks of the ν1 and ν12 modes. However, in the case where the copper or the gold clusters are attached to pyridine, the intensity of the band of the ν12 mode is weakened significantly. We also find that the charge transfer mechanism increases the asymmetry of the bands of the ν1 and ν12 modes on all three metals.

  11. ADSORPTION OF CADMIUM ONTO ORGANIC, TOTAL INORGANIC, AND METAL OXIDE FRACTIONS IN BIOSOLIDS AND BIOSOLID-AMENDED SOILS

    EPA Science Inventory

    The environmental impact and potential hazards of metals in biosolids to plants, animals and the human food chain from biosolids application on soils has been studied for decades. The early hypothesis known as "Time Bomb" has been questioned by recent research results which tend ...

  12. A Dutch Survey on Circumpatellar Electrocautery in Total Knee Arthroplasty

    PubMed Central

    van Jonbergen, Hans-Peter W.; Barnaart, Alexander F.W.; Verheyen, Cees C.P.M.

    2010-01-01

    Introduction: Anterior knee pain following total knee arthroplasty is estimated to occur in 4-49% of patients. Some orthopedic surgeons use circumpatellar electrocautery (diathermy) to reduce the prevalence of postsurgical anterior knee pain; however, the extent of its use is unknown. Materials and Methodology: In April 2009, a postal questionnaire was sent to all 98 departments of orthopedic surgery in The Netherlands. The questions focused on the frequency of total knee arthroplasties, patellar resurfacing, and the use of circumpatellar electrocautery. Results: The response rate was 92%. A total of 18,876 TKAs, 2,096 unicompartmental knee arthroplasties, and 215 patellofemoral arthroplasties are performed yearly in The Netherlands by the responding orthopedic surgeons. Of the orthopedic surgeons performing TKA, 13% always use patellar resurfacing in total knee arthroplasty for osteoarthritis, 49% use selective patellar resurfacing, and 38% never use it. Fifty-six percent of orthopedic surgeons use circumpatellar electrocautery when not resurfacing the patella, and 32% use electrocautery when resurfacing the patella. Conclusion: There is no consensus among Dutch orthopedic surgeons on the use of patellar resurfacing or circumpatellar electrocautery in total knee replacement performed for osteoarthritis. A prospective clinical trial is currently underway to fully evaluate the effect of circumpatellar electrocautery on the prevalence of anterior knee pain following total knee arthroplasty. PMID:21228917

  13. Gene expression influences on metal immunomodulation

    SciTech Connect

    Lynes, Michael A.; Fontenot, Andrew P.; Lawrence, David A.; Rosenspire, Allen J.; Pollard, K. Michael

    2006-01-15

    Heavy metals in the environment originate from both human activities and natural processes. Exposure to these metals can result in important changes to immune activity. Depending on the metal and dose, these changes can result in enhanced immune function, diminished immune responses, or altered responses that produce autoimmune disease. One of the intriguing aspects of these various phenomena are the multiple points of interaction with cellular machinery at which metals elicit these changes. The individual sections of this review serve to underscore the variety of targets that can be altered by exposure to heavy metals, and provide some comparisons between the effects of specific heavy metals on the immune system. These observations may ultimately lead us to a comprehensive understanding of the mechanisms by which metals alter the immune system, and may enable the development of countermeasures to offset these effects.

  14. Fabrication and characterization of metal nanostructures on metal substrates

    NASA Astrophysics Data System (ADS)

    Nikov, Ru. G.; Nedyalkov, N. N.; Atanasov, P. A.; Delaporte, Ph.; Grojo, D.

    2015-01-01

    In this paper we show an experimental procedure for fabrication of metal nanoparticle arrays on metal substrates. The nanostructures are fabricated by laser processing of thin metal films. The films are deposited on the metal substrates by classical PLD technology. The as deposited films are then annealed by nanosecond pulses delivered from a THG Nd:YAG laser system (λ = 355 nm). At certain conditions, the laser treatment leads to a formation of discrete nanoparticle structure on the substrate surface. The optical properties of samples fabricated at different conditions and having different characteristics of the nanostructures are examined by optical spectroscopy measurement. Such analysis shows that the optical spectra of the obtained nanostructures are characterized by plasmon excitation. Finite difference time domain (FDTD) model is used for theoretical description of the near field optical properties of the fabricated nanoparticle arrays. The simulation demonstrates high efficiency of the fabricated structures in enhancement of the near field intensity. The great enhancement observed in the Raman spectra of Rhodamine 6G deposited on the fabricated samples makes such structures very appropriate for applications in Surface Enhanced Raman Spectroscopy (SERS). The produced systems can be also applied in plasmonic solar cells (PSC).

  15. On total internal reflection investigation of nanoparticles by integrated micro-fluidic system.

    PubMed

    Sarov, Yanko E; Capek, Ignac; Ivanov, Tzvetan B; Ivanova, Katerina Zh; Sarova, Valentina A; Rangelow, Ivo W

    2008-02-01

    We report on a novel sensor for characterization of nanoparticles colloidal suspensions. We employ a diffraction grating under total internal reflection for investigation of nanodisperse fluids passing through an integrated microfluidic channel. Dispersions containing polymeric, metallic, and ferromagnetic nanoparticles are studied. Using this device, we can accurately determine in real-time the specific refractive index for the nanoparticle suspension and the nanoparticle concentration. The nanoparticle concentrations can be calculated with a resolution of 0.3-0.5 wt% for polymeric nanoparticles, 0.03-0.05 wt% for metallic nanoparticles, and 0.05-0.1 wt% for ferromagnetic nanoparticles. This translates to an effective refractive index that can be determined with an accuracy of 7 x 10(-4) for the polymeric and 2 x 10(-4) for the metallic and ferromagnetic dispersions. PMID:18163661

  16. Metal Ion Concentrations in Young, Active Patients Following Total Hip Arthroplasty with the Use of Modern Bearing Couples.

    PubMed

    Nam, Denis; Keeney, James A; Nunley, Ryan M; Johnson, Staci R; Clohisy, John C; Barrack, Robert L

    2015-12-01

    The purpose of this study was to compare whole blood metal ion levels in young, active patients undergoing primary total hip arthroplasty with the use of a cobalt-alloy (ten patients), ceramic (15 patients), or oxinium (11 patients) femoral head and highly crosslinked polyethylene acetabular liner. At 2 years postoperatively, mean cobalt concentrations were 3.0 times higher in the cobalt-alloy cohort versus the ceramic cohort, and 2.3 times higher versus the oxinium cohort (P=0.3-0.5). Titanium levels were consistently elevated at all postoperative time points versus preoperatively in all cohorts. Young, active patients following THA demonstrate elevated cobalt and titanium concentrations. Use of a ceramic or oxinium femoral head decreased the degree of cobalt elevation versus a cobalt-alloy femoral head, but did not reach statistical significance. PMID:26164561

  17. Recent progress on the total synthesis of acetogenins from Annonaceae

    PubMed Central

    Li, Nianguang; Shi, Zhihao; Tang, Yuping; Chen, Jianwei

    2008-01-01

    Summary An overview of recent progress on the total synthesis of acetogenins from Annonaceae during the past 12 years is provided. These include mono-tetrahydrofurans, adjacent bis-tetrahydrofurans, nonadjacent bis-tetrahydrofurans, tri-tetrahydrofurans, adjacent tetrahydrofuran-tetrahydropyrans, nonadjacent tetrahydrofuran-tetrahydropyrans, mono-tetrahydropyrans, and acetogenins containing only γ-lactone. This review emphasizes only the first total synthesis of molecules of contemporary interest and syntheses that have helped to correct structures. In addition, some significant results on the novel synthesis and structure–activity relationship studies of annonaceous acetogenins are also introduced. PMID:19190742

  18. Predicting density functional theory total energies and enthalpies of formation of metal-nonmetal compounds by linear regression

    NASA Astrophysics Data System (ADS)

    Deml, Ann M.; O'Hayre, Ryan; Wolverton, Chris; Stevanović, Vladan

    2016-02-01

    The availability of quantitatively accurate total energies (Etot) of atoms, molecules, and solids, enabled by the development of density functional theory (DFT), has transformed solid state physics, quantum chemistry, and materials science by allowing direct calculations of measureable quantities, such as enthalpies of formation (Δ Hf ). Still, the ability to compute Etot and Δ Hf values does not, necessarily, provide insights into the physical mechanisms behind their magnitudes or chemical trends. Here, we examine a large set of calculated Etot and Δ Hf values obtained from the DFT+U -based fitted elemental-phase reference energies (FERE) approach [V. Stevanović, S. Lany, X. Zhang, and A. Zunger, Phys. Rev. B 85, 115104 (2012), 10.1103/PhysRevB.85.115104] to probe relationships between the Etot/Δ Hf of metal-nonmetal compounds in their ground-state crystal structures and properties describing the compound compositions and their elemental constituents. From a stepwise linear regression, we develop a linear model for Etot, and consequently Δ Hf , that reproduces calculated FERE values with a mean absolute error of ˜80 meV/atom. The most significant contributions to the model include calculated total energies of the constituent elements in their reference phases (e.g., metallic iron or gas phase O2), atomic ionization energies and electron affinities, Pauling electronegativity differences, and atomic electric polarizabilities. These contributions are discussed in the context of their connection to the underlying physics. We also demonstrate that our Etot/Δ Hf model can be directly extended to predict the Etot and Δ Hf of compounds outside the set used to develop the model.

  19. The effect of solid metal composition on solid metal/ liquid metal partitioning of trace elements

    NASA Astrophysics Data System (ADS)

    Rai, N.; van Westrenen, W.

    2010-12-01

    Fundamental understanding of the partitioning behaviour of elements between different core and/or mantle phases is needed to constrain processes of planetary differentiation and evolution. The partitioning behaviour of elements between solid metal and liquid metal in the Fe-S system, of relevance to core crystallisation in planetesimals and the terrestrial planets, has been investigated by several workers [1-6], most of whom [1-5] conclude that variations in partition coefficients can be explained by variations in melt composition. However, recently Stewart et al. [6] showed that the crystal-lattice strain model commonly used to describe silicate mineral - silicate melt partitioning can be applied to partially molten metallic systems. This suggests the structure of the solid metal also plays a role in determining solid metal / molten metal partitioning. Here, we investigate the effect of the structure of the solid metal in the Fe-S system on solid/liquid metal partitioning by obtaining new element partitioning data at pressures between 0.5 and 3 GPa. The effect of the solid metal is isolated from pressure-temperature-melt composition effects by performing experiments at constant P and T with two Fe-S bulk compositions on either side of the eutectic composition. In addition to the effect of solid metal composition we investigate the effects of pressure and S content on trace element partitioning behaviour and the application of the lattice strain model to our results. Starting mixtures were doped with several hundred ppm levels of trace elements Ni, Co, W, Mo, V, Nb, Ta, Sn, Cu, Pb, Zn, Cr, Mn, P, Ge,. Experiments were performed using a QUICKPress piston cylinder apparatus at the VU University, Amsterdam using alumina capsules. Experiments were heated to 1073 K at pressure and allowed to sinter for a duration of 10 hours before the temperature was raised at a rate of 50 K / min to the target value. Preliminary EPMA data for a 1 GPa experiment with FeS as the solid

  20. Effects of elevated total dissolved solids on bivalves

    EPA Science Inventory

    A series of experiments were performed to assess the toxicity of different dominant salt recipes of excess total dissolved solids (TDS) to organisms in mesocosms. Multiple endpoints were measured across trophic levels. We report here the effects of four different TDS recipes on b...

  1. A Mini Teaching Sequence on the Totality of Islam.

    ERIC Educational Resources Information Center

    Pellicano, Grace; Pellicano, Roy R.

    1987-01-01

    Provides a secondary teaching unit on the Islamic religious faith and government. Maintains that students must understand the totality of Islam in order to make sense of recent events in Egypt, Morocco, Tunisia, Nigeria, and the Sudan. Included are complete teaching instructions and necessary handouts. (JDH)

  2. Fraunhofer Diffraction Effects on Total Power for a Planckian Source

    PubMed Central

    Shirley, Eric L.

    2001-01-01

    An algorithm for computing diffraction effects on total power in the case of Fraunhofer diffraction by a circular lens or aperture is derived. The result for Fraunhofer diffraction of monochromatic radiation is well known, and this work reports the result for radiation from a Planckian source. The result obtained is valid at all temperatures.

  3. Total Quality Management Practices and Their Effects on Organizational Performance

    ERIC Educational Resources Information Center

    Hung, Richard Yu-Yuan; Lien, Bella Ya-Hui

    2004-01-01

    This paper reports a study designed to examine the key concepts of Total Quality Management (TQM) implementation and their effects on organizational performance. Process Alignment and People Involvement are two key concepts for successful implementation of TQM. The purpose of this paper is to discuss how these two constructs affect organizational…

  4. Photodegradation of chlorofluorocarbon alternatives on metal oxide

    SciTech Connect

    Tanaka, K.; Hisanaga, T. )

    1994-05-01

    HCFC and HFC were photodegraded on metal oxides. Degradation rate on several metal oxides was in the order: TiO[sub 2] > ZnO > Fe[sub 2]O[sub 3] > kaolin [ge] SiO[sub 2] [ge] Al[sub 2]O[sub 3]. Principal degradation products were CO[sub 2], Cl[sup [minus

  5. Total synthesis of buckminsterfullerene (C60) and endohedral metal complexes. Final report, 1 March 1994-28 February 1997

    SciTech Connect

    Rubin, Y.F.

    1997-08-11

    A summary of our work aimed at the synthesis of a variety of endohedral metal complexes of fullerenes is presented. The completion of the synthesis of suitable highly unsaturated macrocyclic precursors containing 60 carbon atoms is described. These compounds were required to study their rearrangement to a fullerene framework in a process analogous to the gas-phase rearrangement of mono- and polycyclic polyynes (acetylenic rings) in the formation of C60 and higher fullerenes. Three types of synthetic acetylenic precursors were targeted, namely triply-linked bis-benzene-cyclophanes with octayne linking units, sextuply-linked bis-benzene-cyclophanes with tetrayne linkers, and deca-alkynylated metallocenes which include a metal in their structure early in the synthesis. The rearrangement to C60 of the first examples of these compounds has been studied in the gas phase by LDMS and in solution by various chemical reactions. Another aspect of our work was initiated by the successful opening of the largest orifice on the framework of C60 known to date in the form of a cobalt(III) complex of ethenobisfulleroid C64H4. This strategy is being applied in a double fashion on adjacent sites of the surface of C60 to form an even larger opening, aimed at eventual metal insertion inside the cage.

  6. Effects of hydrogen on metals

    NASA Technical Reports Server (NTRS)

    Cataldo, C. E.

    1969-01-01

    Several rules to guide choice of materials, and methods of welding, electroplating, and heat treatment will provide a method for minimizing failures in storage tanks and related hardware. Failures are caused by high-pressure hydrogen effects, the formation of hydrides in titanium, and hydrogen absorption through various metals processing techniques.

  7. On the metallicity of open clusters. III. Homogenised sample

    NASA Astrophysics Data System (ADS)

    Netopil, M.; Paunzen, E.; Heiter, U.; Soubiran, C.

    2016-01-01

    Context. Open clusters are known as excellent tools for various topics in Galactic research. For example, they allow accurately tracing the chemical structure of the Galactic disc. However, the metallicity is known only for a rather low percentage of the open cluster population, and these values are based on a variety of methods and data. Therefore, a large and homogeneous sample is highly desirable. Aims: In the third part of our series we compile a large sample of homogenised open cluster metallicities using a wide variety of different sources. These data and a sample of Cepheids are used to investigate the radial metallicity gradient, age effects, and to test current models. Methods: We used photometric and spectroscopic data to derive cluster metallicities. The different sources were checked and tested for possible offsets and correlations. Results: In total, metallicities for 172 open cluster were derived. We used the spectroscopic data of 100 objects for a study of the radial metallicity distribution and the age-metallicity relation. We found a possible increase of metallicity with age, which, if confirmed, would provide observational evidence for radial migration. Although a statistical significance is given, more studies are certainly needed to exclude selection effects, for example. The comparison of open clusters and Cepheids with recent Galactic models agrees well in general. However, the models do not reproduce the flat gradient of the open clusters in the outer disc. Thus, the effect of radial migration is either underestimated in the models, or an additional mechanism is at work. Conclusions: Apart from the Cepheids, open clusters are the best tracers for metallicity over large Galactocentric distances in the Milky Way. For a sound statistical analysis, a sufficiently large and homogeneous sample of cluster metallicities is needed. Our compilation is currently by far the largest and provides the basis for several basic studies such as the statistical

  8. A synopsis on metals in medicine and psychiatry.

    PubMed

    Yung, C Y

    1984-01-01

    A total of 40 metals are reviewed and summarized to give a general perspective on the metal's two major effects, relevant to medicine and psychiatry in man. These two effects are metal excess (poisoning) and deficiency. These metals are grouped arbitrarily into six categories; (a) The heavy metals, (b) the essential and questionable essential trace elements, (c) the macrominerals, (d) the alkali metals, (e) elements used as therapeutic agents, and (f) miscellaneous elements. The heavy metals are invariably toxic and could be lethal, and no deficiency state has yet been described in man, although arsenic has been postulated to be essential. The essential trace elements are vital to a number of vital physiological and biochemical functions, and newer essential trace elements are to be identified in the future. The recent findings suggest vanadium excess may aggravate the affective symptoms in bipolar affective disorder; selenium may inhibit certain carcinogenesis such as oesophageal cancer; and silicon may inhibit atheromatous formation in the aorta. There is also some suggestion that certain allergic syndromes may be correlated with very low levels of iron, copper, manganese. The study of elements will undoubtedly expand the understanding of disease processes in medicine and psychiatry. PMID:6522432

  9. Assessing the risk of metal mixtures in contaminated sediments on Chironomus riparius based on cytosolic accumulation.

    PubMed

    Péry, Alexandre R R; Geffard, Alain; Conrad, Arnaud; Mons, Raphaël; Garric, Jeanne

    2008-11-01

    Sediments usually contain mixtures of trace metals introduced via natural geochemical processes and anthropogenic activities. Kinetics and effects of these metals are strongly dependent both on the composition of the mixture and on the physico-chemical characteristics of the sediment. Relating effects to metal concentration may consequently be advised. However, total accumulation may be a poor predictor of metal toxicity for Chironomus riparius exposed to contaminated field sediments. As an alternative, we proposed to relate effects on Chironomus growth with cytosolic metal accumulation, measured in larvae after a short exposure period. Dose-response relationships were derived for zinc, copper, and cadmium through single-metal exposure data analysed with toxicokinetics and toxicodynamics models. They permitted, on the basis of cytosolic accumulation measures, to predict successfully the effects of mixtures of cadmium, zinc, and copper on the growth of larvae exposed to spiked sediments, as well as to field sediments in which zinc and copper were assumed to be predominant. PMID:18514899

  10. Extreme events in total ozone on global scale

    NASA Astrophysics Data System (ADS)

    Holawe, F.; Rieder, H. E.; Frossard, L.; Ribatet, M.; di Rocco, S.; Maeder, J. A.; Staehelin, J.; Peter, T.; Davison, A. C.; Weihs, P.

    2010-12-01

    We present an application of extreme value theory (Block Maximum/Minimum (BM) models based on the Generalized Extreme Value Distribution) in total ozone research on global scale, comparing the results with standard time series analysis mainly based on mean-value analysis. As statistical analysis showed that previously used concepts assuming a Gaussian distribution of total ozone data do not address the internal data structure concerning extremes adequately recently methods from extreme value theory have been applied for various local and regional case studies in the northern hemisphere. These case studies showed that: (i) tools based on extreme value theory are appropriate to identify ozone extremes and to describe the tails of the total ozone records; (ii) “fingerprints” of atmospheric dynamics (e.g. NAO, ENSO) and chemistry (e.g. ODS, polar vortex ozone loss) and combined dynamical/chemical features (e.g. volcanic eruptions) can be revealed in the frequency of days with extreme low and/or high total ozone; (iii) observed long-term variability and trends are strongly dominated by these extreme events. Within the presented study we analyze extremes in total ozone on large spatial/temporal scale for the northern and southern mid-latitudes (spatial resolution: 1°longitude x 1.5° latitude, temporal resolution: daily values). The results provide deeper inside in the influence of various dynamical and/or physical phenomena (e.g. 11-year solar cycle, QBO, ENSO, NAO, AAO, ODS, volcanic eruptions) on column ozone. Further similarities and differences are analyzed on hemispheric and regional scale. Findings of particular interest concern the large scale spatial pattern of the ENSO in both hemispheres, the NAO in the northern hemisphere and “fingerprints” of the eruption of Mt. Pinatubo in the southern hemisphere (which is in regular mean value analysis almost invisible) that can be set in clear relation to dynamical features such as position and structure of the

  11. The metal to metal interface and its effect on adhesion and friction

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1976-01-01

    The nature of the interface, adhesion and friction properties of noble metals, platinum metals, Group IV (B) metals and transition metals were considered. The surface chemical activity of the noble and platinum metals is shown to effect metal to metal interfaces as does a valance bonding in the transition metals. With the Group IV (B) metals the degree of metallic nature of the elements is shown to effect interfacial behavior. The effect of surface segregation of alloy constituents such as silicon in iron and its influence on the metal to metal interface is discussed. In addition the effect of alloy constituents on changes in bulk properties such as transformations in tin are shown to effect interfacial adhesion and friction behavior.

  12. Aromatic plant production on metal contaminated soils.

    PubMed

    Zheljazkov, Valtcho D; Craker, Lyle E; Xing, Baoshan; Nielsen, Niels E; Wilcox, Andrew

    2008-06-01

    Field and container experiments were conducted to assess the feasibility of growing aromatic crops in metal contaminated areas and the effect of metals on herbage and oil productivity. The field experiments were conducted in the vicinities of the Non-Ferrous Metals Combine (Zn-Cu smelter) near Plovdiv, Bulgaria using coriander, sage, dill, basil, hyssop, lemon balm, and chamomile grown at various distances from the smelter. Herbage essential oil yields of basil, chamomile, dill, and sage were reduced when they were grown closer to the smelter. Metal removal from the site with the harvestable plant parts was as high as 180 g ha(-1) for Cd, 660 g ha(-1) for Pb, 180 g ha(-1) for Cu, 350 g ha(-1) for Mn, and 205 g ha(-1) for Zn. Sequential extraction of soil demonstrated that metal fractionation was affected by the distance to the smelter. With decreasing distance to the smelter, the transfer factor (TF) for Cu and Zn decreased but increased for Cd, while the bioavailability factor (BF) for Cd, Pb, Cu, Mn, and Zn decreased. Scanning electron microscopy and X-ray microanalyses of contaminated soil verified that most of the Pb, Cd, Mn, Cu, and Zn were in the form of small (<1 microm) particles, although there were larger particles (1-5 microm) with high concentrations of individual metals. This study demonstrated that high concentrations of heavy metals in soil or growth medium did not result in metal transfer into the essential oil. Of the tested metals, only Cu at high concentrations may reduce oil content. Our results demonstrated that aromatic crops may not have significant phytoremediation potential, but growth of these crops in metal contaminated agricultural soils is a feasible alternative. Aromatic crops can provide economic return and metal-free final product, the essential oil. PMID:18353428

  13. A note concerning multivariate total positivity on the simplex

    SciTech Connect

    Rayens, W.S.

    1996-12-31

    Although compositional data arise frequently in many different disciplines, relatively little is known about families of parametric densities that reside on a simplex, which is the natural sample space for such data. An exception to this is a recent paper by Gupta and Richards wherein the Liouville family is defined and discussed. They sought to characterize dependence properties within this new family using, among other ideas, multivariate total positivity. Further investigation reveals that their results are not very useful. In fact, it is shown that there does not exist a Liouville density, as defined by Gupta and Richards, that is also multivariate totally positive of order 2. Fatal flaws associated with an obvious alternative to their definition are discussed.

  14. Hybrid regularization image restoration algorithm based on total variation

    NASA Astrophysics Data System (ADS)

    Zhang, Hongmin; Wang, Yan

    2013-09-01

    To reduce the noise amplification and ripple phenomenon in the restoration result by using the traditional Richardson-Lucy deconvolution method, a novel hybrid regularization image restoration algorithm based on total variation is proposed in this paper. The key ides is that the hybrid regularization terms are employed according to the characteristics of different regions in the image itself. At the same time, the threshold between the different regularization terms is selected according to the golden section point which takes into account the human eye's visual feeling. Experimental results show that the restoration results of the proposed method are better than that of the total variation Richardson-Lucy algorithm both in PSNR and MSE, and it has the better visual effect simultaneously.

  15. Effects of background noise on total noise annoyance

    NASA Technical Reports Server (NTRS)

    Willshire, K. F.

    1987-01-01

    Two experiments were conducted to assess the effects of combined community noise sources on annoyance. The first experiment baseline relationships between annoyance and noise level for three community noise sources (jet aircraft flyovers, traffic and air conditioners) presented individually. Forty eight subjects evaluated the annoyance of each noise source presented at four different noise levels. Results indicated the slope of the linear relationship between annoyance and noise level for the traffic noise was significantly different from that of aircraft and of air conditioner noise, which had equal slopes. The second experiment investigated annoyance response to combined noise sources, with aircraft noise defined as the major noise source and traffic and air conditioner noise as background noise sources. Effects on annoyance of noise level differences between aircraft and background noise for three total noise levels and for both background noise sources were determined. A total of 216 subjects were required to make either total or source specific annoyance judgements, or a combination of the two, for a wide range of combined noise conditions.

  16. Influence of biochar amendments on marine sediment trace metal bioavailability

    NASA Astrophysics Data System (ADS)

    Gehrke, G. E.; Hsu-Kim, H.

    2014-12-01

    Biochar has become a desirable material for use in agricultural application to enhance soil quality and in-situ soil and sediment remediation to immobilize organic contaminants. We investigated the effects of biochar sediment amendments on the bioavailability of a suite of inorganic trace metals (Cr, Co, Ni, Cu, Zn, Pb) in contaminated sediments from multiple sites in Elizabeth River, VA. We incubated sediments in microcosms with a variety of water column redox and salinity conditions and compared sediments amended with two types of woody biochar to sediments amended with charcoal activated carbon and unamended sediments. We leached sediments in artificial gut fluid mimic of the benthic invertebrate Arenicola marina as a measure of bioavailability of the trace metals analyzed. In unamended anaerobic sediments, the gut fluid mimic leachable fraction of each trace metal is 1-4% of the total sediment concentration for each metal. Initial results indicate that in anaerobic microcosms, woody biochar sediment amendments (added to 5% dry wt) decrease the gut fluid mimic leachable fraction by 30-90% for all trace metals analyzed, and have comparable performance to charcoal activated carbon amendments. However, in microcosms without controlled redox conditions, woody biochar amendments increase the bioavailable fraction of Ni and Cu by up to 80%, while decreasing the bioavailable fraction of Co, Zn, and Pb by approximately 50%; charcoal activated carbon amendments decreased the bioavailability of all trace metals analyzed by approximately 20%. In microcosms without an overlying water column, biochar and activated carbon amendments had no significant effects on trace metal bioavailability. This research demonstrates that biochar can effectively decrease the bioavailability of trace metals in marine sediments, but its efficiency is metal-specific, and environmental conditions impact biochar performance.

  17. Studies on metal-dielectric plasmonic structures.

    SciTech Connect

    Chettiar, Uday K.; Liu, Zhengtong; Thoreson, Mark D.; Shalaev, Vladimir M.; Drachev, Vladimir P.; Pack, Michael Vern; Kildishev, Alexander V.; Nyga, Piotr

    2010-01-01

    The interaction of light with nanostructured metal leads to a number of fascinating phenomena, including plasmon oscillations that can be harnessed for a variety of cutting-edge applications. Plasmon oscillation modes are the collective oscillation of free electrons in metals under incident light. Previously, surface plasmon modes have been used for communication, sensing, nonlinear optics and novel physics studies. In this report, we describe the scientific research completed on metal-dielectric plasmonic films accomplished during a multi-year Purdue Excellence in Science and Engineering Graduate Fellowship sponsored by Sandia National Laboratories. A variety of plasmonic structures, from random 2D metal-dielectric films to 3D composite metal-dielectric films, have been studied in this research for applications such as surface-enhanced Raman sensing, tunable superlenses with resolutions beyond the diffraction limit, enhanced molecular absorption, infrared obscurants, and other real-world applications.

  18. Total, Direct and Indirect Effects of Paan on Oral Cancer

    PubMed Central

    Merchant, Anwar T; Pitiphat, Waranuch

    2014-01-01

    Purpose Paan (betel leaf and betel nut quid) used with or without tobacco has been positively associated with oral cancer. Oral submucous fibrosis (OSMF), a pre-cancerous condition caused by paan, lies on the causal pathway between paan use and oral cancer. The purpose of this analysis was to estimate the effect of paan consumption on oral cancer risk when it is mediated by OSMF. Methods We used mediation methods proposed by Vanderweele, which are based on causal inference principles, to characterize the total, direct and indirect effects of paan, consumed with and without tobacco, on oral cancer mediated by OSMF. We reanalyzed case-control data collected from three hospitals in Karachi, Pakistan between July 1996 and March 1998. Results For paan without tobacco the total effect on oral cancer was OR=7.39, 95% CI, 1.01, 38.11, natural indirect effect (due to OSMF among paan users) was OR=2.48, 95% CI, 0.99, 10.44, and the natural direct effect (due to paan with OSMF absent) was OR=3.32, 95% CI, 0.68, 10.07. For paan with tobacco the total direct effect was OR=15.68, 95% CI, 3.00, 54.90, natural indirect effect was OR=2.18, 95% CI,0.82, 5.52, and the natural direct effect was OR=7.27, 95% CI,2.15, 20.43. Conclusions Paan, whether or not it contained tobacco, raised oral cancer risk irrespective of OSMF. Oral cancer risk was higher among those who used paan with tobacco. PMID:25542140

  19. Metal fractionation study on bed sediments of River Yamuna, India.

    PubMed

    Jain, C K

    2004-02-01

    The pollution of aquatic ecosystem by heavy metals has assumed serious proportions due to their toxicity and accumulative behavior. The toxicity and fate of the water borne metal is dependent on its chemical form and therefore quantification of the different forms of metal is more meaningful than the estimation of its total metal concentrations. In this study fractionation of metal ions on bed sediments of River Yamuna has been studied to determine the eco-toxic potential of metal ions. The investigations suggest that copper have a tendency to remain associated with residual, reducible and carbonate fractions. The Risk Assessment Code reveal that about 30-50% of lead at most of the sites exist in exchangeable fraction while 30-50% of cadmium at almost all the sites is either exchangeable or carbonate bound and therefore comes under the high risk category and can easily enter the food chain. Most of the copper is in immobile fraction at Delhi while at other sites, a sizable portion (10-30%) is found in carbonate fraction thus posing medium risk for the aquatic environment. Fractionation pattern of zinc shows low to medium risk to aquatic environment. PMID:14723925

  20. Continuum Limit of Total Variation on Point Clouds

    NASA Astrophysics Data System (ADS)

    García Trillos, Nicolás; Slepčev, Dejan

    2016-04-01

    We consider point clouds obtained as random samples of a measure on a Euclidean domain. A graph representing the point cloud is obtained by assigning weights to edges based on the distance between the points they connect. Our goal is to develop mathematical tools needed to study the consistency, as the number of available data points increases, of graph-based machine learning algorithms for tasks such as clustering. In particular, we study when the cut capacity, and more generally total variation, on these graphs is a good approximation of the perimeter (total variation) in the continuum setting. We address this question in the setting of Γ-convergence. We obtain almost optimal conditions on the scaling, as the number of points increases, of the size of the neighborhood over which the points are connected by an edge for the Γ-convergence to hold. Taking of the limit is enabled by a transportation based metric which allows us to suitably compare functionals defined on different point clouds.

  1. Management of metal-on-metal hip implant patients: Who, when and how to revise?

    PubMed

    Berber, Reshid; Skinner, John A; Hart, Alister J

    2016-05-18

    The debate on how best to manage patients with metal-on-metal (MOM) hip implants continues. With over 1 million patients affected worldwide, the impact is far reaching. The majority of the aggressive failures of MOM hip implants have been dealt with by revision hip surgery, leaving patients with a much more indolent pattern of failure of devices that have been in situ for more than 10 years. The longer-term outcome for such patients remains unknown, and much debate exists on how best to manage these patients. Regulatory guidance is available but remains open to interpretation due to the lack of current evidence and long-term studies. Metal ion thresholds for concern have been suggested at 7 ppb for hip resurfacing arthroplasty and below this level for large diameter total hip arthroplasties. Soft tissue changes including pseudotumours and muscle atrophy have been shown to progress, but this is not consistent. New advanced imaging techniques are helping to diagnose complications with metal hips and the reasons for failure, however these are not widely available. This has led to some centres to tackle difficult cases through multidisciplinary collaboration, for both surgical management decisions and also follow-up decisions. We summarise current evidence and consider who is at risk, when revision should be undertaken and how patients should be managed. PMID:27190754

  2. Management of metal-on-metal hip implant patients: Who, when and how to revise?

    PubMed Central

    Berber, Reshid; Skinner, John A; Hart, Alister J

    2016-01-01

    The debate on how best to manage patients with metal-on-metal (MOM) hip implants continues. With over 1 million patients affected worldwide, the impact is far reaching. The majority of the aggressive failures of MOM hip implants have been dealt with by revision hip surgery, leaving patients with a much more indolent pattern of failure of devices that have been in situ for more than 10 years. The longer-term outcome for such patients remains unknown, and much debate exists on how best to manage these patients. Regulatory guidance is available but remains open to interpretation due to the lack of current evidence and long-term studies. Metal ion thresholds for concern have been suggested at 7 ppb for hip resurfacing arthroplasty and below this level for large diameter total hip arthroplasties. Soft tissue changes including pseudotumours and muscle atrophy have been shown to progress, but this is not consistent. New advanced imaging techniques are helping to diagnose complications with metal hips and the reasons for failure, however these are not widely available. This has led to some centres to tackle difficult cases through multidisciplinary collaboration, for both surgical management decisions and also follow-up decisions. We summarise current evidence and consider who is at risk, when revision should be undertaken and how patients should be managed. PMID:27190754

  3. Hip Squeaking after Ceramic-on-ceramic Total Hip Arthroplasty

    PubMed Central

    Wu, Guo-Liang; Zhu, Wei; Zhao, Yan; Ma, Qi; Weng, Xi-Sheng

    2016-01-01

    Objective: The present study aimed to review the characteristics and influencing factors of squeaking after ceramic-on-ceramic (CoC) total hip arthroplasty (THA) and to analyze the possible mechanisms of the audible noise. Data Sources: The data analyzed in this review were based on articles from PubMed and Web of Science. Study Selection: The articles selected for review were original articles and reviews found based on the following search terms: “total hip arthroplasty”, “ceramic-on-ceramic”, “hip squeaking”, and “hip noise.” Results: The mechanism of the squeaking remains unknown. The possible explanations included stripe wear, edge loading, a third body, fracture of the ceramic liner, and resonance of the prosthesis components. Squeaking occurrence is influenced by patient, surgical, and implant factors. Conclusions: Most studies indicated that squeaking after CoC THA was the consequence of increasing wear or impingement, caused by prosthesis design, patient characteristics, or surgical factors. However, as conflicts exist among different articles, the major reasons for the squeaking remain to be identified. PMID:27453238

  4. Detecting contamination on a metal surface

    NASA Technical Reports Server (NTRS)

    Harris, J. M.; Marcus, H. L.; Smith, T.

    1977-01-01

    Thin layers of contaminant on metal surface are detected by measuring surface-potential difference between reference electrode and surface of interest. Procedure does not require mechanical contact with surface under examination.

  5. Wetting of metals and glasses on Mo

    SciTech Connect

    Saiz, Eduardo; Tomsia, Antoni P.; Saiz, Eduardo; Lopez-Esteban, Sonia; Benhassine, Mehdi; de Coninck, Joel; Rauch, Nicole; Ruehle, Manfred

    2008-01-08

    The wetting of low melting point metals and Si-Ca-Al-Ti-O glasses on molybdenum has been investigated. The selected metals (Au, Cu, Ag) form a simple eutectic with Mo. Metal spreading occurs under nonreactive conditions without interdiffusion or ridge formation. The metals exhibit low (non-zero) contact angles on Mo but this requires temperatures higher than 1100 C in reducing atmospheres in order to eliminate a layer of adsorbed impurities on the molybdenum surface. By controlling the oxygen activity in the furnace, glass spreading can take place under reactive or nonreactive conditions. We have found that in the glass/Mo system the contact angle does not decrease under reactive conditions. In all cases, adsorption from the liquid seems to accelerate the diffusivity on the free molybdenum surface.

  6. Trace metal availability and effects on benthic community structure in floodplain lakes.

    PubMed

    van Griethuysen, Corine; van Baren, Joyce; Peeters, Edwin T H M; Koelmans, Albert A

    2004-03-01

    Effects of contaminants on communities are difficult to assess and poorly understood. We analyzed in situ effects of trace metals and common environmental variables on benthic macroinvertebrate communities in floodplain lakes. Alternative measures of trace metal availability were evaluated, including total metals, metals normalized on organic carbon (OC) or clay, simultaneously extracted metals (SEM), combinations of SEM and acid-volatile sulfide (AVS), and metals accumulated by detritivore invertebrates (Oligochaeta). Accumulated metal concentrations correlated positively with sediment trace metals and negatively with surface water dissolved OC. Sixty-eight percent of the variation in benthic community composition was explained by a combination of 11 environmental variables, including sediment, water, and morphological characteristics with trace metals. Metals explained 2 to 6% of the community composition when SEM-AVS or individual SEM concentrations were regarded. In contrast, total, normalized, and accumulated metals were not significantly linked to community composition. We conclude that examination of SEM or SEM - AVS concentrations is useful for risk assessment of trace metals on the community level. PMID:15285361

  7. Synthesis-atomic structure-properties relationships in metallic nanoparticles by total scattering experiments and 3D computer simulations: case of Pt-Ru nanoalloy catalysts.

    PubMed

    Prasai, Binay; Ren, Yang; Shan, Shiyao; Zhao, Yinguang; Cronk, Hannah; Luo, Jin; Zhong, Chuan-Jian; Petkov, Valeri

    2015-05-01

    An approach to determining the 3D atomic structure of metallic nanoparticles (NPs) in fine detail and using the unique knowledge obtained for rationalizing their synthesis and properties targeted for optimization is described and exemplified on Pt-Ru alloy NPs of importance to the development of devices for clean energy conversion such as fuel cells. In particular, PtxRu100-x alloy NPs, where x = 31, 49 and 75, are synthesized by wet chemistry and activated catalytically by a post-synthesis treatment involving heating under controlled N2-H2 atmosphere. So-activated NPs are evaluated as catalysts for gas-phase CO oxidation and ethanol electro-oxidation reactions taking place in fuel cells. Both as-synthesized and activated NPs are characterized structurally by total scattering experiments involving high-energy synchrotron X-ray diffraction coupled to atomic pair distribution functions (PDFs) analysis. 3D structure models both for as-synthesized and activated NPs are built by molecular dynamics simulations based on the archetypal for current theoretical modelling Sutton-Chen method. Models are refined against the experimental PDF data by reverse Monte Carlo simulations and analysed in terms of prime structural characteristics such as metal-to-metal bond lengths, bond angles and first coordination numbers for Pt and Ru atoms. Analysis indicates that, though of a similar type, the atomic structure of as-synthesized and respective activated NPs differ in several details of importance to NP catalytic properties. Structural characteristics of activated NPs and data for their catalytic activity are compared side by side and strong evidence found that electronic effects, indicated by significant changes in Pt-Pt and Ru-Ru metal bond lengths at NP surface, and practically unrecognized so far atomic ensemble effects, indicated by distinct stacking of atomic layers near NP surface and prevalence of particular configurations of Pt and Ru atoms in these layers, contribute to the

  8. Limits on quality of life in communication after total laryngectomy

    PubMed Central

    Chaves, Adriana Di Donato; Pernambuco, Leandro de Araújo; Balata, Patrícia Maria Mendes; Santos, Veridiana da Silva; de Lima, Leilane Maria; de Souza, Síntia Ribeiro; da Silva, Hilton Justino

    2012-01-01

    Summary Introduction: Among people affected by cancer, the impairment of quality of life of people affected by cancer can cause have devastating effects. The self-image of patients after post-laryngectomyzed patients may be find themselves compromised, affecting the quality of life in this population. Objective: To characterize quality of life in related to communication in people who have undergone went total laryngectomy surgery. Methods: This is an observational study, with a cross-sectional and descriptive series. Design of series study. The sample were comprised 15 patients interviewed the period from January to February of 2011. We used the Quality Protocol for Life Communication in Post-laryngectomy adapted from Bertocello (2004); which this questionnaire contains 55 questions. The protocol was organized from the nature of using responses classified as positive and negative aspects, proposals in with respect to five 5 communication domains: family relationships, social relationships, personal analysis; morphofunctional aspect, and use of writing. To promote and guarantee the autonomy of the respondents, was examiners made use of used assistive technology with the Visual Response Scale. Results: The responses that total laryngectomy compromises the quality of life in communication amounted to 463 occurrences (65.7%), and that who responses suggesting good quality of life were represented with amounted to 242 occurrences (34.3%), from a total of 705 occurrencesresponses. From Among the five 5 Communication domains, four 4 had percentages of above 63% for occurrences of negative content for impact on communication. Appearance Morphofunctional appearance gave the had the highest percentage of negative content, amounting to 77.3% of cases. Conclusions: The results showed important limitations of a personal and social nature due to poor communication with their peers. Thus, there is a need for multidisciplinary interventions that aim to minimize the

  9. Selective enrichment of metal-binding proteins based on magnetic core/shell microspheres functionalized with metal cations.

    PubMed

    Fang, Caiyun; Zhang, Lei; Zhang, Xiaoqin; Lu, Haojie

    2015-06-21

    Metal binding proteins play many important roles in a broad range of biological processes. Characterization of metal binding proteins is important for understanding their structure and biological functions, thus leading to a clear understanding of metal associated diseases. The present study is the first to investigate the effectiveness of magnetic microspheres functionalized with metal cations (Ca(2+), Cu(2+), Zn(2+) and Fe(3+)) as the absorbent matrix in IMAC technology to enrich metal containing/binding proteins. The putative metal binding proteins in rat liver were then globally characterized by using this strategy which is very easy to handle and can capture a number of metal binding proteins effectively. In total, 185 putative metal binding proteins were identified from rat liver including some known less abundant and membrane-bound metal binding proteins such as Plcg1, Acsl5, etc. The identified proteins are involved in many important processes including binding, catalytic activity, translation elongation factor activity, electron carrier activity, and so on. PMID:25913209

  10. Long-term observation of water-soluble chemical components and acid-digested metals in the total suspended particles collected at Okinawa, Japan

    NASA Astrophysics Data System (ADS)

    Handa, D.; Okada, K.; Kuroki, Y.; Nakama, Y.; Nakajima, H.; Somada, Y.; Ijyu, M.; Azechi, S.; Oshiro, Y.; Nakaema, F.; Miyagi, Y.; Arakaki, T.; Tanahara, A.

    2011-12-01

    The economic growth and population increase in recent Asia have been increasing air pollution. Emission rate of air pollutants from Asia, in particular oxides of nitrogen, surpassed those from North America and Europe and should continue to exceed them for decades. Okinawa Island is situated approximately 1500 km south of Tokyo, Japan, 2000 km southeast of Beijing, China, and 1000 km south of South Korea. Its location is ideal in observing East Asia's air quality because maritime air mass prevails during summer, while continental air mass dominates during fall, winter, and spring. The maritime air mass data can be seen as background clean air and can be compared with continental air masses which have been affected by anthropogenic activities. We collected total suspended particles (TSP) on quartz filters by using a high volume air sampler at the Cape Hedo Atmosphere and Aerosol Monitoring Station (CHAAMS), Okinawa, Japan during August 2005 and August 2010. Sampling duration was one week for each sample. We determined the concentrations of water-soluble anions, cations, water-soluble organic carbon (WSOC) and acid-digested metals in TSP samples using ion chromatography, atomic absorption spectrometry, total organic carbon analyzer and Inductively Coupled Plasma Mass spectrometry (ICP-MS), respectively. Seasonal variation of water-soluble chemical components and acid-digested metals showed that the concentrations were the lowest in summer, higher in fall and winter, and the highest in spring. When air mass came from Asian continent, the concentrations of water-soluble chemical components and acid-digested metals were much higher compared to the other directions, suggesting long-range transport of air pollutants from Asian continent. Also, when the air mass came from Asian continent (75-100% dominant), the mean concentrations of non-sea salt sulfate and nitrate increased ca. 1.8 times and ca. 3.7 times, respectively between 2005 and 2010, and the ratio of nitrate to

  11. Blood metal ion testing is an effective screening tool to identify poorly performing metal-on-metal bearing surfaces

    PubMed Central

    Sidaginamale, R. P.; Joyce, T. J.; Lord, J. K.; Jefferson, R.; Blain, P. G.; Nargol, A. V. F.; Langton, D. J.

    2013-01-01

    Objectives The aims of this piece of work were to: 1) record the background concentrations of blood chromium (Cr) and cobalt (Co) concentrations in a large group of subjects; 2) to compare blood/serum Cr and Co concentrations with retrieved metal-on-metal (MoM) hip resurfacings; 3) to examine the distribution of Co and Cr in the serum and whole blood of patients with MoM hip arthroplasties; and 4) to further understand the partitioning of metal ions between the serum and whole blood fractions. Methods A total of 3042 blood samples donated to the local transfusion centre were analysed to record Co and Cr concentrations. Also, 91 hip resurfacing devices from patients who had given pre-revision blood/serum samples for metal ion analysis underwent volumetric wear assessment using a coordinate measuring machine. Linear regression analysis was carried out and receiver operating characteristic curves were constructed to assess the reliability of metal ions to identify abnormally wearing implants. The relationship between serum and whole blood concentrations of Cr and Co in 1048 patients was analysed using Bland-Altman charts. This relationship was further investigated in an in vitro study during which human blood was spiked with trivalent and hexavalent Cr, the serum then separated and the fractions analysed. Results Only one patient in the transfusion group was found to have a blood Co > 2 µg/l. Blood/Serum Cr and Co concentrations were reliable indicators of abnormal wear. Blood Co appeared to be the most useful clinical test, with a concentration of 4.5 µg/l showing sensitivity and specificity for the detection of abnormal wear of 94% and 95%, respectively. Generated metal ions tended to fill the serum compartment preferentially in vivo and this was replicated in the in vitro study when blood was spiked with trivalent Cr and bivalent Co. Conclusions Blood/serum metal ion concentrations are reliable indicators of abnormal wear processes. Important differences exist

  12. Effects of Tourniquet Release on Total Knee Arthroplasty.

    PubMed

    Tie, Kai; Hu, Dongcai; Qi, Yongjian; Wang, Hua; Chen, Liaobin

    2016-07-01

    This study investigated the clinical outcomes of early and late tourniquet release (tourniquet release after cementing the prosthesis vs tourniquet release after wound closure and pressure dressing) in total knee arthroplasty (TKA). The study was conducted by searching PubMed, Embase, Web of Science, and Cochrane Central databases for articles on randomized controlled trials comparing early and late tourniquet release in primary TKA that were published from 1966 to March 2015. Relevant data were extracted, and the Physiotherapy Evidence Database (PEDro) Scale was used to assess the methodologic quality. Stata software (StatCorp, College Station, Texas) was used to perform a meta-analysis. Sixteen articles were included with a total of 1073 patients and 1097 knees. For blood loss, there were no significant differences between the 2 groups in calculated blood loss, decrease in hemoglobin level, drop in hematocrit level, and measured postoperative blood loss, although total measured blood loss and postoperative blood transfusion rate were significantly higher in the early tourniquet release group than in the late tourniquet release group. No statistical differences were found for operative time and incidence of deep venous thrombosis (DVT) between the 2 groups. Wound complication rate in the early tourniquet release group was significantly lower than in the late tourniquet release group. Primary TKA with early tourniquet release is similar to TKA with late tourniquet release regarding perioperative blood loss, operative time, and incidence of DVT. Early tourniquet release reduced the incidence of wound complications compared with late tourniquet release. [Orthopedics. 2016; 39(4):e642-e650.]. PMID:27286051

  13. Measurements of Total Hemispherical Emissivity of Several Stably Oxidized Nickel-Titanium Carbide Cemented Hard Metals from 600 F to 1,600 F

    NASA Technical Reports Server (NTRS)

    Wade, William R.; Casey, F. W., Jr.

    1959-01-01

    The total hemispherical emissivity of several nickel-titanium carbide cemented hard metals have been measured over a temperature range from 600 F to l,600 F. A variety of cemented hard metals were obtained from the Kennametal Corporation. A brief discussion of the apparatus employed and the procedures used for this investigation is included. The results of the tests of specimens in the as-received and polished states indicate a nearly constant emissivity for each material tested over the temperature range considered and only slight differences in emissivity values for the different materials. Values obtained on the stably oxidized specimens range from 0.90 to 0.94 at 6000 F and o.88 to 0.92 at 1,600 F for the as-received specimens and from 0.82 to 0.89 at 600 F and 0.85 to 0.87 at 1,600 F for the polished specimens. The surface analysis of the oxidized materials as obtained by X-ray diffraction methods and metallographic techniques are presented as an aid to reproducing the surface on which these measurements were made.

  14. Metallic coatings on silicon substrates, and methods of forming metallic coatings on silicon substrates

    DOEpatents

    Branagan, Daniel J.; Hyde, Timothy A.; Fincke, James R.

    2008-03-11

    The invention includes methods of forming a metallic coating on a substrate which contains silicon. A metallic glass layer is formed over a silicon surface of the substrate. The invention includes methods of protecting a silicon substrate. The substrate is provided within a deposition chamber along with a deposition target. Material from the deposition target is deposited over at least a portion of the silicon substrate to form a protective layer or structure which contains metallic glass. The metallic glass comprises iron and one or more of B, Si, P and C. The invention includes structures which have a substrate containing silicon and a metallic layer over the substrate. The metallic layer contains less than or equal to about 2 weight % carbon and has a hardness of at least 9.2 GPa. The metallic layer can have an amorphous microstructure or can be devitrified to have a nanocrystalline microstructure.

  15. Uptake of metal ions on humic acids

    SciTech Connect

    Pehlivan, E.; Arslan, G.

    2006-09-15

    The kinetics, the sorption capacities, pH and temperature dependence of sorption of humic acids (HAs) of Turkish brown coals with respect to Zn(II), Cu(II), Ni(II), Co(II) and Pb(II) ions were investigated, and the roles of the carboxylic and phenolic groups in the adsorption of metals ion on HAs were searched in this work. These metal ions are able to form complex compounds with carboxylic and phenolic groups of HAs. Adsorption equilibrium was achieved in between 50 and 60 min for all studied cations. HAs extracted from different brown coals have been characterized by chemical and physical methods. The chemical properties of HAs showed differences depending on the source from which they were obtained. The sorption of metals on the surface of HAs depends strongly on the pH, and sorption decreases with decreasing pH. Maximum removal of metal ions was demonstrated at pH values of 4.1-5.0. The Langmuir adsorption isotherm was used to describe observed sorption phenomena. The {Delta}G{sup 0} became negative as the temperature increased, and so the equilibrium constant decreased slightly. The investigation proved that the HAs are suitable materials for the studied heavy metal ion removal from aqueous solution and could be considered as potential material for purification of effluent polluted with toxic metal ions.

  16. [Ceramic-on-ceramic bearings in total hip arthroplasty (THA)].

    PubMed

    Sentürk, U; Perka, C

    2015-04-01

    The main reason for total hip arthroplasty (THA) revision is the wear-related aseptic loosening. Younger and active patients after total joint replacement create high demands, in particular, on the bearings. The progress, especially for alumina ceramic-on-ceramic bearings and mixed ceramics have solved many problems of the past and lead to good in vitro results. Modern ceramics (alumina or mixed ceramics containing alumina) are extremely hard, scratch-resistant, biocompatible, offer a low coefficient of friction, superior lubrication and have the lowest wear rates in comparison to all other bearings in THA. The disadvantage of ceramic is the risk of material failure, i.e., of ceramic fracture. The new generation of mixed ceramics (delta ceramic), has reduced the risk of head fractures to 0.03-0.05 %, but the risk for liner fractures remains unchanged at about 0.02 %. Assuming a non-impinging component implantation, ceramic-on-ceramic bearings have substantial advantages over all other bearings in THA. Due to the superior hardness, ceramic bearings produce less third body wear and are virtually impervious to damage from instruments during the implantation process. A specific complication for ceramic-on-ceramic bearings is "squeaking". The high rate of reported squeaking (0.45 to 10.7 %) highlights the importance of precise implant positioning and the stem and patient selection. With precise implant positioning this problem is rare with many implant designs and without clinical relevance. The improved tribology and the presumable resulting implant longevity make ceramic-on-ceramic the bearing of choice for young and active patients. PMID:25874400

  17. On the ground state of metallic hydrogen

    NASA Technical Reports Server (NTRS)

    Chakravarty, S.; Ashcroft, N. W.

    1978-01-01

    A proposed liquid ground state of metallic hydrogen at zero temperature is explored and a variational upper bound to the ground state energy is calculated. The possibility that the metallic hydrogen is a liquid around the metastable point (rs = 1.64) cannot be ruled out. This conclusion crucially hinges on the contribution to the energy arising from the third order in the electron-proton interaction which is shown here to be more significant in the liquid phase than in crystals.

  18. Hard-on-Hard Total Hip Impingement Causes Extreme Contact Stress Concentrations

    PubMed Central

    Elkins, Jacob M.; O’Brien, Megan K.; Stroud, Nicholas J.; Pedersen, Douglas R.; Callaghan, John J.

    2010-01-01

    Background Impingement events, in addition to their role immediately proximate to frank dislocation, hold the potential to damage new-generation hard-on-hard bearings as a result of the relatively unforgiving nature of the materials and designs. Because of the higher stiffness and tighter design tolerances of metal-on-metal and ceramic implants, surgical positioning plausibly has become even more important. Questions/purposes We asked (1) whether, and under what cup orientation conditions, hard-on-hard impingements might challenge implant material failure strength; and (2) whether particle generation propensity at impingement and egress sites would show similar dependence on cup orientation. Methods Realistic computational simulations were enabled by multistage finite element analyses, addressing both global construct motion and loading, and focal stress concentrations at neck impingement and rim egress sites. The global model, validated by a cadaveric simulation in a servohydraulic hip simulator, included both hardware components and advanced anisotropic capsule characterization. Parametric computational runs explored the effect of cup orientation for both ceramic-on-ceramic and metal-on-metal bearing couples for two distinct motion sequences associated with dislocation. Results Stress concentrations from impingement increased nearly linearly with increased cup tilt and with cup anteversion. In some situations, peak values of stress approached or exceeded 1 GPa, levels challenging the yield strength of cobalt-chromium implants, and potentially the fracture strength of ceramics. The tendency for impingement events to generate debris, indexed in terms of a new scraping severity metric, showed orientation dependences similar to that for bulk material failure. Conclusions Damage propensity arising from impingement events in hard total hip bearings is highly orientation-dependent. PMID:20953853

  19. Bearing surfaces for hip arthroplasty - is metal-on-metal a passing fancy?

    PubMed

    Lee, Reginald K; Nevelos, Jim; Vigdorchik, Jonathan; Markel, David C

    2012-12-01

    Metal-on-metal bearings have had popularity that has waxed and waned over the years. The advantages realized relative to wear resistance and strength had been offset by early failures, manufacturing difficulty, and most recently by adverse soft tissue responses to the metallic debris. The bearing's history, evolution, advantages and disadvantages will be discussed in attempt to answer the question: is metal-on-metal a passing fancy? PMID:23065801

  20. On the total kinetic energy of our Galaxy

    NASA Astrophysics Data System (ADS)

    Ninkovic, Slobodan

    1992-03-01

    The total kinetic energy of the Galaxy is estimated from the potential energy by applying the virial theorem. The limits of the potential energy depend strongly on the value of the local escape velocity. They are estimated to be between (-7 and -1) x 10 exp 16 solar mass sq km/sec sq (escape velocity approximately between 450 km/s and 600 km/s). The specific kinetic energy of the Galaxy as a whole is most likely about 21,000 sq km/sec sq, being equally distributed among the subsystems, if the local escape velocity is near its lower limit; the higher the local escape velocity is, the higher is the specific kinetic energy of the Galaxy due to the influence of the dark corona. The specific kinetic energy of the dark corona tends to become equal to that of the Galaxy as a whole for very high values of the local escape velocity. For the purpose of estimating the total potential energy of the Galaxy, inter alia, a model of the Milky Way is developed which yields both the potential and the density analytically so that it is suitable for calculating the galactocentric orbits.

  1. The Effect of Total Thyroidectomy on the Speech Production

    PubMed Central

    Yang, Yun Su; Lee, Hyun Doo; Yoon, Yun Sub; Hong, Yong Tae

    2015-01-01

    Objectives Voice and speech alternations that can occur after total thyroidectomy are usually due to recurrent or superior laryngeal nerve injury. These alterations may also be associated with other extralaryngeal factors, such as neck muscle dysfunction and scar contracture of the neck. We performed a prospective acoustic analysis on speech changes after surgery, in the absence of laryngeal nerve injury. Methods Patients aged 19 to 58 years undergoing total thyroidectomy, in the absence of laryngeal/pulmonary disease, previous neck surgery, or other malignant diseases, were recruited prospectively. For the running speech analysis, the speaking fundamental frequencies (SFo), range of SFo and speaking intensity were evaluated before surgery, 7 days, and 1 and 3 months after surgery. For consonant analysis, the acoustic distinctions of stop consonant, the voice onset time (VOT), vowel duration and closure duration were evaluated at the same periods. Results SFo and range of SFo were specifically diminished after surgery, while speaking intensities were not changed significantly after surgery. The thyroidectomized speakers displayed systematically varied VOT for the consonant production, which was phonetically representative. However, VOT after surgery could be longer in the strong aspirated and glottalized stops, but not in the lax stop than before surgery. The vowel and closure durations were not affected before and after surgery. Conclusion Patients with thyroidectomy have some difficulty of pitch control and consonant articulation during speaking. VOT is also one of the meaningful acoustic parameters and provide a reference for comparing acoustic measures before and after thyroidectomy. PMID:26045915

  2. Evaluation on bioactivities of total flavonoids from Lavandula angustifolia.

    PubMed

    Zhao, Jun; Xu, Fang; Huang, Hua; Ji, Tengfei; Li, Chenyang; Tan, Wei; Chen, Yan; Ma, Long

    2015-07-01

    Lavandula angustifolia was used to treat flus and fevers, joint swelling and pain in Uighur medicine. This study aimed to investigate antioxidant, antit anti-inflammatory and antalgic noids content (530.1mg/g rutin/g dry extract) with stronger DPPH scavenging abilities and reduciactivities of total flavonoids from Lavandula angustifolia (LTF). Results indicated that LTF possesses the highest total flavong power. Some flavonoids separated from LTF, and their DPPH scavenging abilities as follows: rosmarinic acid (2, near to Vit C) >luteolin (3) >apigenin (4) >luteolin 7-O-β-D-glucoside (5) >apigenin 7-O-β-D-glucoside (6) >luteolin 7-O-β-D-glucuronide (7). LTF significantly decreased malondialdehyde (MDA) level in D-galactose induced aging model compared to the control group (P<0.05), as well as significantly increased plasma superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities (P<0.05). Moreover, 17.4, 34.8 and 69.6 mg/kg doses of LTF were exhibited significant analgesic and anti-inflammatory activities in a dose dependent manner (P<0.05). Cytotoxicity of LTF on Bel-7402 and Hela cell lines were showed by MTT assay also. These results verified traditional usage of this plant and suggested also that LTF is worth developing and studying further. PMID:26142514

  3. The Effect of QBO on the Total Mass Density

    NASA Astrophysics Data System (ADS)

    Saǧır, Selçuk; Atıcı, Ramazan

    2016-07-01

    The relationship between Quasi-Biennial Oscillation (QBO) measured at 10 hPa altitude and total mass density (TMD) values obtained from NRLMSIS-00 model for 90 km altitude of ionosphere known as Mesosphere-Lower Thermosphere (MLT) region is statistically investigated. For this study, multiple-regression model is used. To see the effect on TMD of QBO directions, Dummy variables are also added to model. In the result of calculations, it is observed that QBO is effected on TMD. It is determined that 69% of variations at TMD can be explainable by QBO. It is determined that the explainable ratio is at the rate of 5%. Also, it is seen that an increase/a decrease of 1 meter per second at QBO give rise to an increase/a decrease of 7,2x10-4 g/cm3 at TMD.

  4. Structural evolution across the insulator-metal transition in oxygen-deficient BaTiO3-δ studied using neutron total scattering and Rietveld analysis

    SciTech Connect

    Jeong, I.-K.; Lee, Seunghun; Jeong, Se-Young; Won, C. J.; Hur, N.; Llobet, A.

    2011-08-29

    Oxygen-deficient BaTiO3-δ exhibits an insulator-metal transition with increasing δ. We performed neutron total scattering measurements to study structural evolution across an insulator-metal transition in BaTiO3-δ. Despite its significant impact on resistivity, slight oxygen reduction (δ=0.09) caused only a small disturbance on the local doublet splitting of Ti-O bond. This finding implies that local polarization is well preserved under marginal electric conduction. In the highly oxygen-deficient metallic state (δ=0.25), however, doublet splitting of the Ti-O bond became smeared. The smearing of the local Ti-O doublet is complemented with long-range structural analysis and demonstrates that the metallic conduction in the highly oxygen-reduced BaTiO3-δ is due to the appearance of nonferroelectric cubic lattice.

  5. Total Body Irradiation, Toward Optimal Individual Delivery: Dose Evaluation With Metal Oxide Field Effect Transistors, Thermoluminescence Detectors, and a Treatment Planning System

    SciTech Connect

    Bloemen-van Gurp, Esther J. Mijnheer, Ben J.; Verschueren, Tom A.M.; Lambin, Philippe

    2007-11-15

    Purpose: To predict the three-dimensional dose distribution of our total body irradiation technique, using a commercial treatment planning system (TPS). In vivo dosimetry, using metal oxide field effect transistors (MOSFETs) and thermoluminescence detectors (TLDs), was used to verify the calculated dose distributions. Methods and Materials: A total body computed tomography scan was performed and loaded into our TPS, and a three-dimensional-dose distribution was generated. In vivo dosimetry was performed at five locations on the patient. Entrance and exit dose values were converted to midline doses using conversion factors, previously determined with phantom measurements. The TPS-predicted dose values were compared with the MOSFET and TLD in vivo dose values. Results: The MOSFET and TLD dose values agreed within 3.0% and the MOSFET and TPS data within 0.5%. The convolution algorithm of the TPS, which is routinely applied in the clinic, overestimated the dose in the lung region. Using a superposition algorithm reduced the calculated lung dose by approximately 3%. The dose inhomogeneity, as predicted by the TPS, can be reduced using a simple intensity-modulated radiotherapy technique. Conclusions: The use of a TPS to calculate the dose distributions in individual patients during total body irradiation is strongly recommended. Using a TPS gives good insight of the over- and underdosage in a patient and the influence of patient positioning on dose homogeneity. MOSFETs are suitable for in vivo dosimetry purposes during total body irradiation, when using appropriate conversion factors. The MOSFET, TLD, and TPS results agreed within acceptable margins.

  6. Some stars are totally metal: a new mechanism driving dust across star-forming clouds, and consequences for planets, stars, and galaxies

    SciTech Connect

    Hopkins, Philip F.

    2014-12-10

    Dust grains in neutral gas behave as aerodynamic particles, so they can develop large local density fluctuations entirely independent of gas density fluctuations. Specifically, gas turbulence can drive order-of-magnitude 'resonant' fluctuations in the dust density on scales where the gas stopping/drag timescale is comparable to the turbulent eddy turnover time. Here we show that for large grains (size ≳ 0.1 μm, containing most grain mass) in sufficiently large molecular clouds (radii ≳ 1-10 pc, masses ≳ 10{sup 4} M {sub ☉}), this scale becomes larger than the characteristic sizes of prestellar cores (the sonic length), so large fluctuations in the dust-to-gas ratio are imprinted on cores. As a result, star clusters and protostellar disks formed in large clouds should exhibit significant abundance spreads in the elements preferentially found in large grains (C, O). This naturally predicts populations of carbon-enhanced stars, certain highly unusual stellar populations observed in nearby open clusters, and may explain the 'UV upturn' in early-type galaxies. It will also dramatically change planet formation in the resulting protostellar disks, by preferentially 'seeding' disks with an enhancement in large carbonaceous or silicate grains. The relevant threshold for this behavior scales simply with cloud densities and temperatures, making straightforward predictions for clusters in starbursts and high-redshift galaxies. Because of the selective sorting by size, this process is not necessarily visible in extinction mapping. We also predict the shape of the abundance distribution—when these fluctuations occur, a small fraction of the cores may actually be seeded with abundances Z ∼ 100 (Z) such that they are almost 'totally metal' (Z ∼ 1)! Assuming the cores collapse, these totally metal stars would be rare (1 in ∼10{sup 4} in clusters where this occurs), but represent a fundamentally new stellar evolution channel.

  7. Impact of metals on the biodegradation of organic pollutants.

    PubMed Central

    Sandrin, Todd R; Maier, Raina M

    2003-01-01

    Forty percent of hazardous waste sites in the United States are co-contaminated with organic and metal pollutants. Data from both aerobic and anaerobic systems demonstrate that biodegradation of the organic component can be reduced by metal toxicity. Metal bioavailability, determined primarily by medium composition/soil type and pH, governs the extent to which metals affect biodegradation. Failure to consider bioavailability rather than total metal likely accounts for much of the enormous variability among reports of inhibitory concentrations of metals. Metals appear to affect organic biodegradation through impacting both the physiology and ecology of organic degrading microorganisms. Recent approaches to increasing organic biodegradation in the presence of metals involve reduction of metal bioavailability and include the use of metal-resistant bacteria, treatment additives, and clay minerals. The addition of divalent cations and adjustment of pH are additional strategies currently under investigation. PMID:12826480

  8. Oxygen tensioactivity on liquid-metal drops.

    PubMed

    Ricci, E; Arato, E; Passerone, A; Costa, P

    2005-12-14

    The influence of oxygen on the surface tension of liquid metals is a topic of undoubted interest as the formation of oxide films, or even oxygen contamination of the metal interface, represents the main source of error in determining the surface tension. The evaluation of gas-atmosphere mass exchanges under stationary conditions allows the evaluation of an effective oxygen pressure at which the oxidation of metal becomes evident. This effective oxygen pressure can be considered as a property of the system and, according to experimental evidence, can be many orders of magnitude greater than the equilibrium pressure. The measurement of the surface tension is a good way of studying interface properties, their temporal change and their connections to transport and reaction rates. This paper represents a review of a work undertaken with the aim of understanding oxygen mass transport at the liquid metal surface in relation to the study of capillary phenomena at high temperature. PMID:16098947

  9. USEPA METHOD STUDY 35 - SW-846 METHOD 3005, ACID DIGESTION OF WATERS FOR TOTAL RECOVERABLE OR DISSOLVED METALS FOR ANALYSES BY FLAME ATOMIC ABSORPTION SPECTROSCOPY

    EPA Science Inventory

    An interlaboratory collaborative study was conducted to determine the precision and bias (recovery) of Solid Waste (SW) Method 3005 for the analysis of 21 elements in ground water. SW Method 3005 is entitled, "Acid Digestion of Waters for Total Recoverable Metals for Analyses by ...

  10. Effects of irradiation on alaryngeal voice of totally laryngectomized patients

    SciTech Connect

    Izdebski, K.; Fontanesi, J.; Ross, J.C.; Hetzler, D.

    1988-06-01

    The effects of radiation therapy on the ability of totally laryngectomized patients to produce voice and speech were examined using objective non-invasive methods. Moderate to severe losses were noted in patients producing voice with all types of alaryngeal modalities: tracheoesophageal, esophageal, and electrolaryngeal. Voice and speech losses were related to the impaired motility and vibratory capability of the esophageal wall and mucosa, to fibrosis of the submandibular region and to trismus. Tracheoesophageal and esophageal voice was recovered some weeks after completion of irradiation. No voice losses were observed in alaryngeal speakers who did not undergo voice restoration until after irradiation. All irradiated patients also showed various degrees of dysphagia during the treatment.

  11. In situ induced metal-enhanced fluorescence: a new strategy for biosensing the total acetylcholinesterase activity in sub-microliter human whole blood.

    PubMed

    Ma, KeKe; Lu, Lu; Qi, Zongli; Feng, Jingjing; Zhuo, Caixia; Zhang, Yaodong

    2015-06-15

    Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities (i.e., total AChE) in human blood are biomarkers for theranostic monitoring of organophosphate neurotoxin-poisoned patients. We developed an ultra-sensitive method to detect the total AChE activity in sub-microliter human whole blood based on in situ induced metal-enhanced fluorescence (MEF). Both AChE and BChE can catalyze the hydrolysis of the acetylthiocholine (ATCh) substrate and produce positively-charged thiocholine (TCh). TCh can reverse the negatively-charged surface of core-shell Ag@SiO2 nanoparticles (NPs). The negatively-charged fluorescent dye (8-hydroxypyrene-1,3,6-trisulfonic acid, HPTS) is then confined to the surface of Ag@SiO2 NPs and generates an enhanced fluorescence signal in situ. Changes in the surface charge of Ag@SiO2 NPs are monitored by Zeta potential, and the MEF effect is confirmed by the measurements of fluorescence time decay. AChE activity has a dynamic range of 0 U/mL to 0.005 U/mL and a detection limit of 0.05 mU/mL. The total AChE activity in the sub-microliter human whole blood could be determined; the results were further validated. Therefore, combining the AChE catalytic reaction with MEF provides a simple, ultra-sensitive, and cost-effective "in situ MEF" approach to determine the total AChE activity in human whole blood sample down to sub-microliters without matrix interferences. The strategy also allows potential usage in other tissues and other fields. PMID:25660508

  12. Graphene film growth on polycrystalline metals.

    PubMed

    Edwards, Rebecca S; Coleman, Karl S

    2013-01-15

    Graphene, a true wonder material, is the newest member of the nanocarbon family. The continuous network of hexagonally arranged carbon atoms gives rise to exceptional electronic, mechanical, and thermal properties, which could result in the application of graphene in next generation electronic components, energy-storage materials such as capacitors and batteries, polymer nanocomposites, transparent conducting electrodes, and mechanical resonators. With one particularly attractive application, optically transparent conducting electrodes or films, graphene has the potential to rival indium tin oxide (ITO) and become a material for producing next generation displays, solar cells, and sensors. Typically, graphene has been produced from graphite using a variety of methods, but these techniques are not suitable for growing large-area graphene films. Therefore researchers have focused much effort on the development of methodology to grow graphene films across extended surfaces. This Account describes current progress in the formation and control of graphene films on polycrystalline metal surfaces. Researchers can grow graphene films on a variety of polycrystalline metal substrates using a range of experimental conditions. In particular, group 8 metals (iron and ruthenium), group 9 metals (cobalt, rhodium, and iridium), group 10 metals (nickel and platinum), and group 11 metals (copper and gold) can support the growth of these films. Stainless steel and other commercial copper-nickel alloys can also serve as substrates for graphene film growth. The use of copper and nickel currently predominates, and these metals produce large-area films that have been efficiently transferred and tested in many electronic devices. Researchers have grown graphene sheets more than 30 in. wide and transferred them onto display plastic ready for incorporation into next generation displays. The further development of graphene films in commercial applications will require high

  13. On the variation of the Nimbus 7 total solar irradiance

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    1992-01-01

    For the interval December 1978 to April 1991, the value of the mean total solar irradiance, as measured by the Nimbus-7 Earth Radiation Budget Experiment channel 10C, was 1,372.02 Wm(exp -2), having a standard deviation of 0.65 Wm(exp -2), a coefficient of variation (mean divided by the standard deviation) of 0.047 percent, and a normal deviate z (a measure of the randomness of the data) of -8.019 (inferring a highly significant non-random variation in the solar irradiance measurements, presumably related to the action of the solar cycle). Comparison of the 12-month moving average (also called the 13-month running mean) of solar irradiance to those of the usual descriptors of the solar cycle (i.e., sunspot number, 10.7-cm solar radio flux, and total corrected sunspot area) suggests possibly significant temporal differences. For example, solar irradiance is found to have been greatest on or before mid 1979 (leading solar maximum for cycle 21), lowest in early 1987 (lagging solar minimum for cycle 22), and was rising again through late 1990 (thus, lagging solar maximum for cycle 22), having last reported values below those that were seen in 1979 (even though cycles 21 and 22 were of comparable strength). Presuming a genuine correlation between solar irradiance and the solar cycle (in particular, sunspot number) one infers that the correlation is weak (having a coefficient of correlation r less than 0.84) and that major excursions (both as 'excesses' and 'deficits') have occurred (about every 2 to 3 years, perhaps suggesting a pulsating Sun).

  14. Prevalence of Pseudotumor in Patients After Metal-On-Metal Hip Arthroplasty Evaluated with Metal Ion Analysis and MARS-MRI.

    PubMed

    Sutphen, Sean A; MacLaughlin, Lewis H; Madsen, Adam A; Russell, Jackie H; McShane, Michael A

    2016-01-01

    The purpose of this study is to quantify the prevalence of pseudotumors in patients with well-functioning and painful metal-on-metal total hip arthroplasty, to characterize the pseudotumor with the use of MARS-MRI, and to assess the relationship between pseudotumors and metal ions. We retrospectively reviewed 102 single surgeon patients. The results showed that 68.6% developed pseudotumor with 60.9% of the asymptomatic group developing pseudotumor. The symptomatic group had a higher proportion of patients with elevated serum cobalt levels (P=0.035). There was no difference found with elevated metal ions and prevalence of pseudotumor, but elevated cobalt levels were associated with larger pseudotumor size (P=0.001). The available evidence indicated that most patients that develop pseudotumors are asymptomatic, and that elevated serum cobalt levels may be associated with symptoms and pseudotumor size. PMID:26253484

  15. Total protein

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/003483.htm Total protein To use the sharing features on this page, please enable JavaScript. The total protein test measures the total amount of two classes ...

  16. Fire severity effects on ash extractable Total Phosphorous

    NASA Astrophysics Data System (ADS)

    Pereira, Paulo; Úbeda, Xavier; Martin, Deborah

    2010-05-01

    Phosphorous (P) is a crucial element to plant nutrition and limits vegetal production. The amounts of P in soil are lower and great part of this nutrient is absorbed or precipitated. It is well known that fire has important implications on P cycle, that can be lost throughout volatilization, evacuated with the smoke, but also more available to transport after organic matter mineralization imposed by the fire. The release of P depends on ash pH and their chemical and physical characteristics. Fire temperatures impose different severities, according to the specie affected and contact time. Fire severity is often evaluated by ash colour and this is a low-cost and excellent methodology to assess the fire effects on ecosystems. The aim of this work is study the ash properties physical and chemical properties on ash extractable Total Phosphorous (TP), collected in three wildfires, occured in Portugal, (named, (1) Quinta do Conde, (2) Quinta da Areia and (3) Casal do Sapo) composed mainly by Quercus suber and Pinus pinaster trees. The ash colour was assessed using the Munsell color chart. From all three plots we analyzed a total of 102 ash samples and we identified 5 different ash colours, ordered in an increasing order of severity, Very Dark Brown, Black, Dark Grey, Very Dark Grey and Light Grey. In order to observe significant differences between extractable TP and ash colours, we applied an ANOVA One Way test, and considered the differences significant at a p<0.05. The results showed that significant differences in the extractable TP among the different ash colours. Hence, to identify specific differences between each ash colour, we applied a post-hoc Fisher LSD test, significant at a p<0.05. The results obtained showed significant differences between the extractable TP from Very dark Brown and Black ash, produced at lower severities, in relation to Dark Grey, Very Dark Grey and Light Grey ash, generated at higher severities. The means of the first group were higher

  17. Physicochemical processes on the solid metal-molten metal interface

    SciTech Connect

    Eremenko, V.N.; Dybkov, V.I.; Natanzon, Y.V.

    1985-05-01

    The authors present a method of dissolution by which bimetalspecimens of St3 and 45 steels, 12Kh18N1OT stainless steel with A995 aluminum, ADl and silumin were obtained. Tests showed high mechanical strength of the bimetals and good resistance under thermal shock conditions. The authors further conclude that the method of creation of permanent joints of metals by holding the solid, more refractory metal with a liquid low-melting one is most suitable for the production of cylindrical bimetal blanks since in this case it is easy to agitate the molten metal by rotation of the original blank of the solid metal in it. By simple machining from such a bimetal, it is possible to obtain tubes, butt joints or concentric two- and three-layer sleeves.

  18. An Examination of the Association of Selected Toxic Metals with Total and Central Obesity Indices: NHANES 99-02

    PubMed Central

    Padilla, Miguel A.; Elobeid, Mai; Ruden, Douglas M.; Allison, David B.

    2010-01-01

    It is conceivable that toxic metals contribute to obesity by influencing various aspects of metabolism, such as by substituting for essential micronutrients and vital metals, or by inducing oxidative stress. Deficiency of the essential metal zinc decreases adiposity in humans and rodent models, whereas deficiencies of chromium, copper, iron, and magnesium increases adiposity. This study utilized the NHANES 99-02 data to explore the association between waist circumference and body mass index with the body burdens of selected toxic metals (barium, cadmium, cobalt, cesium, molybdenum, lead, antimony, thallium, and tungsten). Some of the associations were significant direct relationships (barium and thallium), and some of the associations were significant inverse relationships (cadmium, cobalt, cesium, and lead). Molybdenum, antimony, and tungsten had mostly insignificant associations with waist circumference and body mass index. This is novel result for most of the toxic metals studied, and a surprising result for lead because high stored lead levels have been shown to correlate with higher rates of diabetes, and obesity may be a key risk factor for developing diabetes. These associations suggest the possibility that environmental exposure to metals may contribute to variations in human weight gain/loss. Future research, such as prospective studies rather than the cross-sectional studies presented here, is warranted to confirm these findings. PMID:20948927

  19. Preliminary total dose measurements on LDEF. [long duration exposure facility

    NASA Technical Reports Server (NTRS)

    Reitz, G.

    1992-01-01

    After spending nearly six years in Earth's orbit twenty stacks consisting of radiation detectors and biological objects are now back on Earth. These Free Flyer Biostack experiments are part of the Long Duration Exposure Facility (LDEF). The major objective of the experiments are to investigate the biological effectiveness of single heavy ions of the cosmic radiation in various biological systems and to provide information about the spectral composition of the radiation field and the total dose received in the LDEF orbit. The preliminary analysis of the thermoluminescence dosimeters (TLD) yields maximum absorbed dose rates of 2.24 mGy day(exp -1) behind 0.7 g cm(exp -2) shielding and 1.17 mGy day(exp -1) behind 12 g cm(exp -2) shielding. A thermal neutron fluence of 1.7 n cm(exp -2)s(exp -1) is determined from the differences in absorbed dose for different isotopic mixtures of lithium. The results of this experiment on LDEF are especially valuable since LDEF stayed for almost six years in the prospected orbit of the Space Station Freedom.

  20. Metal bioavailability in freshwater sediment samples and their influence on ecological status of river basins.

    PubMed

    Roig, Neus; Sierra, Jordi; Moreno-Garrido, Ignacio; Nieto, Elena; Gallego, Elena Pérez; Schuhmacher, Marta; Blasco, Julián

    2016-01-01

    The general aim of this work has been to check the ecological impact of metals on the Ebro river basin. In order to evaluate this, metal behavior considering water, sediment as well as metal bioaccumulation in fish has been studied. Total concentrations of metals, as well as the potentially bioavailable fraction of metals in sediment has also been analyzed by the application of the sequential extraction method (BCR method). In order to evaluate the influence of metal pollution on the river ecological status, according to the Water Framework Directive (WFD), diverse biological indices such as macroinvertebrates (IBMWP), diatoms (IPS) and macrophytes (IVAM), have been considered from an integrated point of view. Considering both water and sediment, metals which contributed in higher extend to the reduction of biological quality have been demonstrated to be Pb and Zn, as they presented a negative influence on macroinvertebrates, diatoms and macrophytes communities. As and Cr that seemed to have a significant influence on macroinvertebrates and diatoms too, while Ni negatively influenced only diatom communities. This study also demonstrated that monitoring programs only based on total metal determination in water are inefficient, as metals present even at undetectable concentrations in water are strongly accumulated in fish. Moreover, the high concentrations of Hg found in sediments indicated that this river basin may present pollution problems regarded to this metal, as demonstrated by the high Hg levels found in fish. PMID:26148425

  1. The metal to metal interface and its effect on adhesion and friction

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1976-01-01

    The paper considers the interface between two bulk metals and the effect of this interface on adhesive bonding, resistance to tangential displacements, friction and the interfacial transport from one surface to another. Using Auger emission spectroscopy, field ion microscopy, and low energy electron diffraction techniques, the influence of surface orientation, lattice registry, crystal lattice structure and defects, metal surface chemistry and alloying on the characteristics of the interface was studied for noble, platinum, transition, and Group 4B metals. With dissimilar metals in contact, epitaxial transfer of the cohesively weaker to the cohesively stronger metal has been observed. Surface chemical activity of the noble and platinum metals is shown to affect interfacial behavior as does a valence bonding in the transition metals, and the degree of metallic nature in the Group 4B elements. Alloying elements, e.g., Si and Fe, can alter interfacial behavior by segregation to the surface of metals or by altering bulk properties such as crystal transformation kinetics.

  2. Microfocus study of metal distribution and speciation in tissue extracted from revised metal on metal hip implants

    NASA Astrophysics Data System (ADS)

    Hart, Alister J.; Sandison, Ann; Quinn, Paul; Sampson, Barry; Atkinson, Kirk D.; Skinner, John A.; Goode, Angela; Powell, Jonathan J.; Mosselmans, J. Frederick W.

    2009-11-01

    Unexplained tissue inflammation in metal-on-metal hip replacements is suspected to be caused by implant-derived nanoparticles. The aim of this study was to investigate the nature of the metal particles in tissue surrounding metal-on-metal (MOM) hips that has been extracted during revision. Mapping of tissue surrounding the failed MOM hips was performed using microfocus X-ray Fluorescence (XRF). This revealed mainly Cr which was localized to the cellular regions. There was co-localisation of Co, were present, to areas of high Cr abundance. XANES of the tissue and appropriate standards revealed that the most common species were Cr(III) and Co(II). EXAFS analysis of the tissue and various metal standards revealed that the most abundant implant-related species was Cr(III) phosphate. Different tissue preparation methods, including frozen sectioning, were examined but were found not to affect the distribution or speciation of the metals in the tissue.

  3. Hyperspectral Image Target Detection Improvement Based on Total Variation.

    PubMed

    Yang, Shuo; Shi, Zhenwei

    2016-05-01

    For the hyperspectral target detection, the neighbors of a target pixel are very likely to be target pixels, and those of a background pixel are very likely to be background pixels. In order to utilize this spatial homogeneity or smoothness, based on total variation (TV), we propose a novel supervised target detection algorithm which uses a single target spectrum as the prior knowledge. TV can make the image smooth, and has been widely used in image denoising and restoration. The proposed algorithm uses TV to keep the spatial homogeneity or smoothness of the detection output. Meanwhile, a constraint is used to guarantee the spectral signature of the target unsuppressed. The final formulated detection model is an ℓ1-norm convex optimization problem. The split Bregman algorithm is used to solve our optimization problem, as it can solve the ℓ1-norm optimization problem efficiently. Two synthetic and two real hyperspectral images are used to do experiments. The experimental results demonstrate that the proposed algorithm outperforms the other algorithms for the experimental data sets. The experimental results also show that even when the target occupies only one pixel, the proposed algorithm can still obtain good results. This is because in such a case, the background is kept smooth, but at the same time, the algorithm allows for sharp edges in the detection output. PMID:27019489

  4. Towards nanoprinting with metals on graphene

    PubMed Central

    Melinte, G.; Moldovan, S.; Hirlimann, C.; Liu, X.; Bégin-Colin, S.; Bégin, D.; Banhart, F.; Pham-Huu, C.; Ersen, O.

    2015-01-01

    Graphene and carbon nanotubes are envisaged as suitable materials for the fabrication of the new generation of nanoelectronics. The controlled patterning of such nanostructures with metal nanoparticles is conditioned by the transfer between a recipient and the surface to pattern. Electromigration under the impact of an applied voltage stands at the base of printing discrete digits at the nanoscale. Here we report the use of carbon nanotubes as nanoreservoirs for iron nanoparticles transfer on few-layer graphene. An initial Joule-induced annealing is required to ensure the control of the mass transfer with the nanotube acting as a ‘pen' for the writing process. By applying a voltage, the tube filled with metal nanoparticles can deposit metal on the surface of the graphene sheet at precise locations. The reverse transfer of nanoparticles from the graphene surface to the nanotube when changing the voltage polarity opens the way for error corrections. PMID:26314620

  5. Towards nanoprinting with metals on graphene

    NASA Astrophysics Data System (ADS)

    Melinte, G.; Moldovan, S.; Hirlimann, C.; Liu, X.; Bégin-Colin, S.; Bégin, D.; Banhart, F.; Pham-Huu, C.; Ersen, O.

    2015-08-01

    Graphene and carbon nanotubes are envisaged as suitable materials for the fabrication of the new generation of nanoelectronics. The controlled patterning of such nanostructures with metal nanoparticles is conditioned by the transfer between a recipient and the surface to pattern. Electromigration under the impact of an applied voltage stands at the base of printing discrete digits at the nanoscale. Here we report the use of carbon nanotubes as nanoreservoirs for iron nanoparticles transfer on few-layer graphene. An initial Joule-induced annealing is required to ensure the control of the mass transfer with the nanotube acting as a `pen' for the writing process. By applying a voltage, the tube filled with metal nanoparticles can deposit metal on the surface of the graphene sheet at precise locations. The reverse transfer of nanoparticles from the graphene surface to the nanotube when changing the voltage polarity opens the way for error corrections.

  6. Tribolayer Formation in a Metal-on-Metal (MoM) Hip Joint: An Electrochemical Investigation

    PubMed Central

    Mathew, MT; Nagelli, C; Pourzal, R; Fischer, A; Laurent, MP; Jacobs, JJ; Wimmer, MA

    2013-01-01

    The demand for total hip replacement (THR) surgery is increasing in the younger population due to faster rehabilitation and more complete restoration of function. Up to 2009, metal-on-metal (MoM) hip joint bearings were a popular choice due to their design flexibility, post-operative stability and relatively low wear rates. The main wear mechanisms that occur along the bearing surface of MoM joints are tribochemical reactions that deposit a mixture of wear debris, metal ions and organic matrix of decomposed proteins known as a tribolayer. No in-depth electrochemical studies have been reported on the structure and characteristics of this tribolayer or about the parameters involved in its formation. In this study, we conducted an electrochemical investigation of different surfaces (bulk-like: control, nano-crystalline: new implant and tribolayer surface: retrieved implant) made out of two commonly used hip CoCrMo alloys (high-carbon and low-carbon). As per ASTM standard, cyclic polarization tests and electrochemical impedance spectroscopy tests were conducted. The results obtained from electrochemical parameters for different surfaces clearly indicated a reduction in corrosion for the tribolayer surface (Icorr: 0.76 μA/cm2). Further, polarization resistance (Rp:2.39±0.60MΩ/cm2) and capacitance (Cdl:15.20±0.75 μF/cm2) indicated variation in corrosion kinetics for the tribolayer surface, that attributed to its structure and stability in a simulated body environment. PMID:24099949

  7. ION EXCHANGE SOFTENING: EFFECTS ON METAL CONCENTRATIONS

    EPA Science Inventory

    A corrosion control pipe loop study to evaluate the effect of ion exchange water softening on metal leaching from household plumbing materials was conducted on two different water qualities having different pH's and hardness levels. The results showed that removing hardness ions ...

  8. Effect of heavy metals on bacterial transport

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Olson, M. S.

    2010-12-01

    Adsorption of metals onto bacteria and soil takes place as stormwater runoff infiltrates into the subsurface. Changes in both bacterial surfaces and soil elemental content have been observed, and may alter the attachment of bacteria to soil surfaces. In this study, scanning electron microscopy (SEM) and Energy Dispersive X-ray Spectrometry (EDS) analyses were performed on soil samples equilibrated with synthetic stormwater amended with copper, lead and zinc. The results demonstrate the presence of copper and zinc on soil surfaces. To investigate bacterial attachment behavior, sets of batch sorption experiments were conducted on Escherichia Coli (E. coli) under different chemical conditions by varying solution compositions (nutrient solution vs synthetic stormwater). The adsorption data is best described using theoretical linear isotherms. The equilibrium coefficient (Kd) of E. coli is higher in synthetic stormwater than in nutrient solution without heavy metals. The adsorption of heavy metals onto bacterial surfaces significantly decreases their negative surface charge as determined via zeta potential measurements (-17.0±5.96mv for E. coli equilibrated with synthetic stormwater vs -21.6±5.45mv for E. coli equilibrated with nutrient solution), indicating that bacterial attachment may increase due to the attachment of metals onto bacterial surfaces and their subsequent change in surface charge. The attachment efficiency (α) of bacteria was also calculated and compared for both solution chemistries. Bacterial attachment efficiency (α) in synthetic stormwater is 0.997, which is twice as high as that in nutrient solution(α 0.465). The ratio of bacterial diameter : collector diameter suggests minimal soil straining during bacterial transport. Results suggest that the presence of metals in synthetic stormwater leads to an increase in bacterial attachment to soil surfaces. In terms of designing stormwater infiltration basins, the presence of heavy metals seems to

  9. Effects of earthworms on metal uptake of heavy metals from polluted mine soils by different crop plants.

    PubMed

    Ruiz, E; Rodríguez, L; Alonso-Azcárate, J

    2009-05-01

    A pot experiment was conducted in order to assess the effect of the earthworm Eisenia fetida on the uptake of Pb, Zn, Cd and Cu from soils polluted by mining activities using maize (Zea mays) and barley (Hordeum vulgare). Results from single and sequential extractions showed that the soil chemical partitioning of heavy metals was significantly changed by E. fetida, leading to a higher concentration of metals in the non-residual fractions of the soil. Earthworm activities significantly increased shoot biomass (65% for maize and 73% for barley) and root metal concentration for all the metals under study in both maize and barley. The total accumulation rate values for Cd, Cu, Pb and Zn were significantly higher in the presence of E. fetida for both crop plants. Those latter effects led to an increase in Zn extraction yields of up to 3.7-fold and 2.3-fold for barley and maize, respectively. PMID:19232427

  10. Synthesis-atomic structure-properties relationships in metallic nanoparticles by total scattering experiments and 3D computer simulations: case of Pt-Ru nanoalloy catalysts

    NASA Astrophysics Data System (ADS)

    Prasai, Binay; Ren, Yang; Shan, Shiyao; Zhao, Yinguang; Cronk, Hannah; Luo, Jin; Zhong, Chuan-Jian; Petkov, Valeri

    2015-04-01

    An approach to determining the 3D atomic structure of metallic nanoparticles (NPs) in fine detail and using the unique knowledge obtained for rationalizing their synthesis and properties targeted for optimization is described and exemplified on Pt-Ru alloy NPs of importance to the development of devices for clean energy conversion such as fuel cells. In particular, PtxRu100-x alloy NPs, where x = 31, 49 and 75, are synthesized by wet chemistry and activated catalytically by a post-synthesis treatment involving heating under controlled N2-H2 atmosphere. So-activated NPs are evaluated as catalysts for gas-phase CO oxidation and ethanol electro-oxidation reactions taking place in fuel cells. Both as-synthesized and activated NPs are characterized structurally by total scattering experiments involving high-energy synchrotron X-ray diffraction coupled to atomic pair distribution functions (PDFs) analysis. 3D structure models both for as-synthesized and activated NPs are built by molecular dynamics simulations based on the archetypal for current theoretical modelling Sutton-Chen method. Models are refined against the experimental PDF data by reverse Monte Carlo simulations and analysed in terms of prime structural characteristics such as metal-to-metal bond lengths, bond angles and first coordination numbers for Pt and Ru atoms. Analysis indicates that, though of a similar type, the atomic structure of as-synthesized and respective activated NPs differ in several details of importance to NP catalytic properties. Structural characteristics of activated NPs and data for their catalytic activity are compared side by side and strong evidence found that electronic effects, indicated by significant changes in Pt-Pt and Ru-Ru metal bond lengths at NP surface, and practically unrecognized so far atomic ensemble effects, indicated by distinct stacking of atomic layers near NP surface and prevalence of particular configurations of Pt and Ru atoms in these layers, contribute to the

  11. Total Dose Effects on Single Event Transients in Digital CMOS and Linear Bipolar Circuits

    NASA Technical Reports Server (NTRS)

    Buchner, S.; McMorrow, D.; Sibley, M.; Eaton, P.; Mavis, D.; Dusseau, L.; Roche, N. J-H.; Bernard, M.

    2009-01-01

    This presentation discusses the effects of ionizing radiation on single event transients (SETs) in circuits. The exposure of integrated circuits to ionizing radiation changes electrical parameters. The total ionizing dose effect is observed in both complementary metal-oxide-semiconductor (CMOS) and bipolar circuits. In bipolar circuits, transistors exhibit grain degradation, while in CMOS circuits, transistors exhibit threshold voltage shifts. Changes in electrical parameters can cause changes in single event upset(SEU)/SET rates. Depending on the effect, the rates may increase or decrease. Therefore, measures taken for SEU/SET mitigation might work at the beginning of a mission but not at the end following TID exposure. The effect of TID on SET rates should be considered if SETs cannot be tolerated.

  12. Multivitamin-multimineral supplements' effect on total nutrient intake.

    PubMed

    Murphy, Suzanne P; White, Kami K; Park, Song-Yi; Sharma, Sangita

    2007-01-01

    Use of multivitamin-multimineral supplements is widespread and can contribute substantially to total nutrient intakes. In the Hawaii-Los Angeles Multiethnic Cohort (MEC), 48% of men and 56% of women without chronic diseases reported use of multivitamin supplements at least weekly over the past year. We calculated the prevalence of nutrient adequacy for 17 nutrients based on responses to a self-administered quantitative food-frequency questionnaire administered to MEC participants at baseline in 1993-1996. Although the prevalence of nutrient adequacy from food only was higher for multivitamin supplement users (n = 21,056) than for nonusers (n = 69,715), differences averaged only 2 percentage points. For multivitamin users, the prevalence of adequacy improved by an average of 8 percentage points for both men and women when intake from supplements was included. Users were also more likely to have potentially excessive intakes, particularly for iron, zinc, vitamin A, and niacin. The 26,735 MEC participants in Hawaii who answered an open-ended question about multivitamin use in 1999-2001 reported using 1246 different products. The nutrient profile of these products varied widely, and the composition of products at the 90th percentile was 10-fold greater than the composition at the median for some nutrients. We conclude that analyses of nutrient adequacy and excess for supplement users should be extended to national samples and that composition data on actual supplements used are preferable to assuming a default nutrient profile for multivitamin supplements. Multivitamin products could be better formulated to reduce the prevalence of inadequacy and also to reduce the risk of excessive intakes. PMID:17209210

  13. Balancing innovation and medical device regulation: the case of modern metal-on-metal hip replacements.

    PubMed

    Howard, Jason J

    2016-01-01

    Due to problems with wear particle generation and subsequent loosening using conventional metal-on-polyethylene total hip replacements, there has been a shift toward alternative bearing systems, including metal-on-metal (MoM), for younger, more active patients with degenerative joint disease. Based on positive results from early short-term clinical studies, MoM hip replacements were readily adopted by orthopedic surgeons with thousands being implanted worldwide over the past decade. Unacceptably high revision rates reported by two national joint registries called into question the rigorousness of the regulatory approval process for these implants, particularly with respect to premarket data requirements to prove safety, effectiveness, and the appropriateness of the regulatory pathway chosen. The purpose of this review was to investigate the balance between facilitating the introduction of new medical technologies and the need to ensure safety and effectiveness through comprehensive regulatory assessment. The case of MoM hip replacement devices was used to frame the investigation and subsequent discussions. The regulatory approval processes and post-market surveillance requirements associated with three common MoM hip replacements (two resurfacings: the Birmingham and articular surface replacement and the articular surface replacement XL total hip replacement) were investigated. With respect to modern MoM hip replacement devices, the balance between facilitating the introduction of these new medical technologies and the need to ensure safety and effectiveness through comprehensive regulatory assessment was not achieved. The lessons learned from these experiences have application beyond joint replacements to the introduction of new medical technologies in general, particularly for those who have a significant potential for harm. In this regard, a series of recommendations have been developed to contribute to the evolution of the medical device regulatory process

  14. Balancing innovation and medical device regulation: the case of modern metal-on-metal hip replacements

    PubMed Central

    Howard, Jason J

    2016-01-01

    Due to problems with wear particle generation and subsequent loosening using conventional metal-on-polyethylene total hip replacements, there has been a shift toward alternative bearing systems, including metal-on-metal (MoM), for younger, more active patients with degenerative joint disease. Based on positive results from early short-term clinical studies, MoM hip replacements were readily adopted by orthopedic surgeons with thousands being implanted worldwide over the past decade. Unacceptably high revision rates reported by two national joint registries called into question the rigorousness of the regulatory approval process for these implants, particularly with respect to premarket data requirements to prove safety, effectiveness, and the appropriateness of the regulatory pathway chosen. The purpose of this review was to investigate the balance between facilitating the introduction of new medical technologies and the need to ensure safety and effectiveness through comprehensive regulatory assessment. The case of MoM hip replacement devices was used to frame the investigation and subsequent discussions. The regulatory approval processes and post-market surveillance requirements associated with three common MoM hip replacements (two resurfacings: the Birmingham and articular surface replacement and the articular surface replacement XL total hip replacement) were investigated. With respect to modern MoM hip replacement devices, the balance between facilitating the introduction of these new medical technologies and the need to ensure safety and effectiveness through comprehensive regulatory assessment was not achieved. The lessons learned from these experiences have application beyond joint replacements to the introduction of new medical technologies in general, particularly for those who have a significant potential for harm. In this regard, a series of recommendations have been developed to contribute to the evolution of the medical device regulatory process

  15. Formability Evaluation of Sheet Metals Based on Global Strain Distribution

    NASA Astrophysics Data System (ADS)

    Zhang, Ling; Lin, Jianping; Min, Junying; Ye, You; Kang, Liugen

    2016-04-01

    According to the conventional methods for formability evaluation, e.g., forming limit curve (FLC), limit dome height, and total elongation, inconsistent results are observed when comparing the formability of four advanced high-strength steels (AHSS) with an ultimate tensile strength grade of 1000 MPa. The strain distribution analysis with the aid of digital image correlation technique shows that different uniform deformation capabilities of sheet metals under the same loading conditions are responsible for this inconsistency. In addition, metallurgical analysis suggests that inhomogeneous microstructure distribution and phase transformation during deformation in some materials play important roles in the uniform deformation capability of sheet metal. Limit strains on the commonly used FLC only relate to the major and minor strains of local deforming elements associated with the onset of necking. However, the formability of a sheet metal component is determined by the strain magnitudes of all deforming elements involved during the forming process. Hence, the formability evaluation of sheet metals from a global aspect is more applicable for practical engineering. A new method based on two indices (i.e., which represent global formability and uniform deformation capability, respectively) is proposed to evaluate the formability of sheet metals based on global strain distribution. The formability and evolution of deformation uniformity of the investigated AHSS at different stress states are studied with this new method. Compared with other formability evaluation methods, the new method is demonstrated to be more appropriate for practical engineering, and it is applicable to both in-plane and out-of-plane deformation. Additionally, the global formability of sheet metals can be more comprehensively understood with this new method.

  16. Formability Evaluation of Sheet Metals Based on Global Strain Distribution

    NASA Astrophysics Data System (ADS)

    Zhang, Ling; Lin, Jianping; Min, Junying; Ye, You; Kang, Liugen

    2016-06-01

    According to the conventional methods for formability evaluation, e.g., forming limit curve (FLC), limit dome height, and total elongation, inconsistent results are observed when comparing the formability of four advanced high-strength steels (AHSS) with an ultimate tensile strength grade of 1000 MPa. The strain distribution analysis with the aid of digital image correlation technique shows that different uniform deformation capabilities of sheet metals under the same loading conditions are responsible for this inconsistency. In addition, metallurgical analysis suggests that inhomogeneous microstructure distribution and phase transformation during deformation in some materials play important roles in the uniform deformation capability of sheet metal. Limit strains on the commonly used FLC only relate to the major and minor strains of local deforming elements associated with the onset of necking. However, the formability of a sheet metal component is determined by the strain magnitudes of all deforming elements involved during the forming process. Hence, the formability evaluation of sheet metals from a global aspect is more applicable for practical engineering. A new method based on two indices (i.e., which represent global formability and uniform deformation capability, respectively) is proposed to evaluate the formability of sheet metals based on global strain distribution. The formability and evolution of deformation uniformity of the investigated AHSS at different stress states are studied with this new method. Compared with other formability evaluation methods, the new method is demonstrated to be more appropriate for practical engineering, and it is applicable to both in-plane and out-of-plane deformation. Additionally, the global formability of sheet metals can be more comprehensively understood with this new method.

  17. Chemisorption on supported-metal catalysts

    NASA Astrophysics Data System (ADS)

    Davison, S. G.; Bose, S. M.; Sulston, K. W.

    1988-07-01

    A Gree-function formalism is developed to describe the electronic and chemisorption properties of a supported-metal composite substrate. Within the framework of the tight-binding approximation, the metal catalyst is represented by a finite chain of d-orbitals, while the semi-infinite semiconductor support is characterized by a linear chain of alternating s- and p-orbitals. The Anderson-Newns model is used to calculate the chemisorption energy and adatom charge transfer for hydrogen chemisorption on the Ni/ZnO composite system.

  18. Ultrasound screening of periarticular soft tissue abnormality around metal-on-metal bearings.

    PubMed

    Nishii, Takashi; Sakai, Takashi; Takao, Masaki; Yoshikawa, Hideki; Sugano, Nobuhiko

    2012-06-01

    Although metal hypersensitivity or pseudotumors are concerns for metal-on-metal (MoM) bearings, detailed pathologies of patterns, severity, and incidence of periprosthetic soft tissue lesions are incompletely understood. We examined the potential of ultrasound for screening of periarticular soft tissue lesions around MoM bearings. Ultrasound examinations were conducted in 88 hips (79 patients) with MoM hip resurfacings or MoM total hip arthroplasties with a large femoral head. Four qualitative ultrasound patterns were shown, including normal pattern in 69 hips, joint-expansion pattern in 11 hips, cystic pattern in 5 hips, and mass pattern in 3 hips. Hips with the latter 3 abnormal patterns showed significantly higher frequency of clinical symptoms, without significant differences of sex, duration of implantation, head sizes, and cup abduction/anteversion angles, compared with hips with normal pattern. Ultrasound examination provides sensitive screening of soft tissue reactions around MoM bearings and may be useful in monitoring progression and defining treatment for periarticular soft tissue abnormalities. PMID:22047978

  19. High-emittance coatings on metal substrates

    NASA Technical Reports Server (NTRS)

    Emanuelson, R. C.; Luoma, W. L.; Walek, W. J.

    1968-01-01

    High-emittance coatings of iron, calcium, and zirconium titanates thermally sprayed on stainless steel, columbium-1 percent zirconium, and beryllium substrates promote and control radiative heat transfer from the metal substrates. Adherence, compatibility and emittance stability at elevated temperature and high vacuum were evaluated.

  20. Buffer layers on biaxially textured metal substrates

    DOEpatents

    Shoup, Shara S.; Paranthamam, Mariappan; Beach, David B.; Kroeger, Donald M.; Goyal, Amit

    2001-01-01

    A method is disclosed for forming a biaxially textured buffer layer on a biaxially oriented metal substrate by using a sol-gel coating technique followed by pyrolyzing/annealing in a reducing atmosphere. This method is advantageous for providing substrates for depositing electronically active materials thereon.

  1. The influence of nitrilotriacetate on heavy metal uptake of lettuce and ryegrass

    SciTech Connect

    Kulli, B.; Balmer, M.; Krebs, R.; Lothenbach, B.; Geiger, G.; Schulin, R.

    1999-12-01

    Metal uptake and removal from the soil by plants may be a useful measure to remediate contaminated soils. These processes can be enhanced by adding metal chelators to soil. The authors investigated the effect of nitrolotriacetate (NTA) and urea on the uptake of Cd, Cu, and Zn by lettuce (Lactuca sativa L. ev. Orion) and Italian ryegrass (Lolium perenne L. ev. Bastion) in pot experiments. Nitric acid-extractable heavy metal concentrations in the contaminated soil were 2 mg Cd, 530 mg Cu, and 700 mg Zn/kg. Three NTA treatments were compared with two urea treatments, and a control. Nitrilotriacetate and urea increased the NaNO{sub 3}-extractable soil concentrations of the three metals. At the highest NTA dose, metal concentrations in the aboveground plant biomass was 4 to 24 times greater than in the control plants. While NTA increased plant metal concentrations, it reduced plant matter production. At lower doses, this effect was small. At the highest NTA dose, plant growth was almost completely inhibited. Severe visual symptoms indicated metal toxicity as the likely cause. The urea treatments generally increased the plant matter production. Total metal uptake was in general larger at the lowest or at the intermediate NTA dose than at the highest doses. Little additional total metal uptake was achieved with NTA treatments than with urea. Compared with the controls, neither NTA nor urea enhanced total uptake under the given conditions by more than threefold.

  2. Report on the Total System Computer Program for Medical Libraries.

    ERIC Educational Resources Information Center

    Divett, Robert T.; Jones, W. Wayne

    The objective of this project was to develop an integrated computer program for the total operations of a medical library including acquisitions, cataloging, circulation, reference, a computer catalog, serials controls, and current awareness services. The report describes two systems approaches: the batch system and the terminal system. The batch…

  3. Notes on TQM (Total Quality Management) and Education

    ERIC Educational Resources Information Center

    Daniel, Carter A.

    2005-01-01

    Application of Deming's TQM principles to education is long overdue. Principles that have proven their worth in businesses for decades could revolutionize our thinking about education. But they require a total commitment, from the highest to the lowest level. Deming's 14 points, and Gray Rinehart's suggestions, are presented, discussed, and…

  4. Chemoelectronic circuits based on metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Yan, Yong; Warren, Scott C.; Fuller, Patrick; Grzybowski, Bartosz A.

    2016-07-01

    To develop electronic devices with novel functionalities and applications, various non-silicon-based materials are currently being explored. Nanoparticles have unique characteristics due to their small size, which can impart functions that are distinct from those of their bulk counterparts. The use of semiconductor nanoparticles has already led to improvements in the efficiency of solar cells, the processability of transistors and the sensitivity of photodetectors, and the optical and catalytic properties of metal nanoparticles have led to similar advances in plasmonics and energy conversion. However, metals screen electric fields and this has, so far, prevented their use in the design of all-metal nanoparticle circuitry. Here, we show that simple electronic circuits can be made exclusively from metal nanoparticles functionalized with charged organic ligands. In these materials, electronic currents are controlled by the ionic gradients of mobile counterions surrounding the ‘jammed’ nanoparticles. The nanoparticle-based electronic elements of the circuitry can be interfaced with metal nanoparticles capable of sensing various environmental changes (humidity, gas, the presence of various cations), creating electronic devices in which metal nanoparticles sense, process and ultimately report chemical signals. Because the constituent nanoparticles combine electronic and chemical sensing functions, we term these systems ‘chemoelectronic’. The circuits have switching times comparable to those of polymer electronics, selectively transduce parts-per-trillion chemical changes into electrical signals, perform logic operations, consume little power (on the scale of microwatts), and are mechanically flexible. They are also ‘green’, in the sense that they comprise non-toxic nanoparticles cast at room temperature from alcohol solutions.

  5. Chemoelectronic circuits based on metal nanoparticles.

    PubMed

    Yan, Yong; Warren, Scott C; Fuller, Patrick; Grzybowski, Bartosz A

    2016-07-01

    To develop electronic devices with novel functionalities and applications, various non-silicon-based materials are currently being explored. Nanoparticles have unique characteristics due to their small size, which can impart functions that are distinct from those of their bulk counterparts. The use of semiconductor nanoparticles has already led to improvements in the efficiency of solar cells, the processability of transistors and the sensitivity of photodetectors, and the optical and catalytic properties of metal nanoparticles have led to similar advances in plasmonics and energy conversion. However, metals screen electric fields and this has, so far, prevented their use in the design of all-metal nanoparticle circuitry. Here, we show that simple electronic circuits can be made exclusively from metal nanoparticles functionalized with charged organic ligands. In these materials, electronic currents are controlled by the ionic gradients of mobile counterions surrounding the 'jammed' nanoparticles. The nanoparticle-based electronic elements of the circuitry can be interfaced with metal nanoparticles capable of sensing various environmental changes (humidity, gas, the presence of various cations), creating electronic devices in which metal nanoparticles sense, process and ultimately report chemical signals. Because the constituent nanoparticles combine electronic and chemical sensing functions, we term these systems 'chemoelectronic'. The circuits have switching times comparable to those of polymer electronics, selectively transduce parts-per-trillion chemical changes into electrical signals, perform logic operations, consume little power (on the scale of microwatts), and are mechanically flexible. They are also 'green', in the sense that they comprise non-toxic nanoparticles cast at room temperature from alcohol solutions. PMID:26974958

  6. Metal-On-Metal Bonding and Rebonding Revisited

    SciTech Connect

    Bogicevic, A.

    1999-02-23

    Density-functional calculations for a wide variety of metals show that, contrary to the rebonding view of adsorbate bonding, addimers do not have notably longer surface bonds than adatoms, do not reside farther above the surface, and do not meet the rebonding arguments for augmented mobility. Rebonding concepts are found to have some utility in explaining addimer stability.

  7. Removal of Metallic Iron on Oxide Slags

    NASA Astrophysics Data System (ADS)

    Shannon, George N.; Fruehan, R. J.; Sridhar, Seetharaman

    2009-10-01

    It is possible, in some cases, for ground coal particles to react with gasifier gas during combustion, allowing the ash material in the coal to form phases besides the expected slag phase. One of these phases is metallic iron, because some gasifiers are designed to operate under a reducing atmosphere ({p_{O2}} of approximately 10-4 atm). Metallic iron can become entrained in the gas stream and deposit on, and foul, downstream equipment. To improve the understanding of the reaction between different metallic iron particles and gas, which eventually oxidizes them, and the slag that the resulting oxide dissolves in, the kinetics of iron reaction on slag were predicted using gas-phase mass-transfer limitations for the reaction and were compared with diffusion in the slag; the reaction itself was observed under confocal scanning laser microscopy. The expected rates for iron droplet removal are provided based on the size and effective partial pressure of oxygen, and it is found that decarburization occurs before iron reaction, leading to an extra 30- to 100-second delay for carbon-saturated particles vs pure iron particles. A pure metallic iron particle of 0.5 mg should be removed in about 220 seconds at 1400 °C and in 160 seconds at 1600 °C.

  8. Removal of metallic iron on oxide slags

    SciTech Connect

    Shannon, G.N.; Fruehan, R.J.; Sridhar, S.

    2009-10-15

    It is possible, in some cases, for ground coal particles to react with gasifier gas during combustion, allowing the ash material in the coal to form phases besides the expected slag phase. One of these phases is metallic iron, because some gasifiers are designed to operate under a reducing atmosphere (pO{sub 2}) of approximately 10{sup -4} atm). Metallic iron can become entrained in the gas stream and deposit on, and foul, downstream equipment. To improve the understanding of the reaction between different metallic iron particles and gas, which eventually oxidizes them, and the slag that the resulting oxide dissolves in, the kinetics of iron reaction on slag were predicted using gas-phase mass-transfer limitations for the reaction and were compared with diffusion in the slag; the reaction itself was observed under confocal scanning laser microscopy. The expected rates for iron droplet removal are provided based on the size and effective partial pressure of oxygen, and it is found that decarburization occurs before iron reaction, leading to an extra 30- to 100-second delay for carbon-saturated particles vs pure iron particles. A pure metallic iron particle of 0.5 mg should be removed in about 220 seconds at 1400{sup o}C and in 160 seconds at 1600{sup o}C.

  9. Application of patent bio-rack wetland system using Phragmites sp. for domestic wastewater treatment in the presence of high total dissolved solids (TDS) and heavy metal salts.

    PubMed

    Valipour, Alireza; Raman, V Kalyan; Ghole, V S

    2011-07-01

    The quality of water recourses is degrading due to improper wastewater management. The aim of this study is to examine the potential of bio-rack system for treatment of domestic wastewater in the presence of high total dissolved solids (TDS) and heavy metal salts. The bio-rack is a modified wetland system incorporated with the advantages of phytoremediation and attached growth microbial process. The bio-rack is void of the soil strata based root zone system and in lieu a support matrix is provided to enrich the micro flora. The studies indicate that, Phragmites sp. can tolerate TDS up to 9000 mg/L in the bio-rack. The heavy metal removal is a function of phytoaccumulation or phytoextraction, which can lead to morphological deformity if heavy metals exceed the saturation limit of 786 and 5760 mg/kg Cd, 854 and 9280 mg/kg Cu, 639 and 4720 mg/kg Ni, 1187 and 7516 mg/kg Zn, in shoots and roots respectively. The reduction in TDS is marginal (14%) at the highest tolerable limit whereas the heavy metal reduction is 68%, 69%, 67%, 71% for Cd, Cu, Ni and Zn respectively at the outlet of the treatment system. The sewage treatment performance of the bio-rack system for all other parameters is estimated as 75 % Chemical Oxygen Demand (COD), 86 % Biological Oxygen Demand (BOD5), 27% Total Dissolved Solids (TDS), 73% Total Suspended Solids (TSS), 9% chlorides, 70% ammonia nitrogen (NH3-N), 32% phosphate (PO4-P), 92% most probable number (MPN) and 93% total viable count (TVC) reduction. PMID:23029929

  10. Effects of heavy metal pollution on oak leaf microorganisms

    SciTech Connect

    Bewley, R.J.F.

    1980-12-01

    During the growing season, comparisons wer made of the leaf surface microflora of (i) two groups of mature oak trees, one in the vicinity of a smelting complex contaminated by heavy metals and the other at a relatively uncontaminated site, and (ii) two groups of oak saplings at the uncontaminated site, one of which was sprayed with zinc, lead, and cadmium to simulate the heavy metal pollution from the smelter without the complicating effects of other pollutants. Total viable counts of bacteria, yeasts, and filamentous fungi (isolated by leaf washing) were generally little affected by the spraying treatment, whereas polluted leaves of mature trees supported fewer bacteria compared with leaves of mature trees at the uncontaminated site. Numbers of pigmented yeasts were lower on polluted oaks and on metal-dosed saplings compared with their respective controls. Polluted leaves of mature trees supported both greater numbers of Aureobasidium pullulans and Cladosporium spp. and a greater percentage of metal-tolerant fungi compared with oak leaves at the uncontaminated site. There were no significant overall differences in the degree of mycelial growth between the two groups of saplings or the mature trees.

  11. Effects of Heavy Metal Pollution on Oak Leaf Microorganisms

    PubMed Central

    Bewley, Richard J. F.

    1980-01-01

    During the growing season, comparisons were made of the leaf surface microflora of (i) two groups of mature oak trees, one in the vicinity of a smelting complex contaminated by heavy metals and the other at a relatively uncontaminated site, and (ii) two groups of oak saplings at the uncontaminated site, one of which was sprayed with zinc, lead, and cadmium to simulate the heavy metal pollution from the smelter without the complicating effects of other pollutants. Total viable counts of bacteria, yeasts, and filamentous fungi (isolated by leaf washing) were generally little affected by the spraying treatment, whereas polluted leaves of mature trees supported fewer bacteria compared with leaves of mature trees at the uncontaminated site. Numbers of pigmented yeasts were lower on polluted oaks and on metal-dosed saplings compared with their respective controls. Polluted leaves of mature trees supported both greater numbers of Aureobasidium pullulans and Cladosporium spp. and a greater percentage of metal-tolerant fungi compared with oak leaves at the uncontaminated site. There were no significant overall differences in the degree of mycelial growth between the two groups of saplings or the mature trees. PMID:16345669

  12. Dietary exposure to metals and other elements in the 2006 UK Total Diet Study and some trends over the last 30 years.

    PubMed

    Rose, M; Baxter, M; Brereton, N; Baskaran, C

    2010-10-01

    Concentrations of 24 elements including metals in the 2006 UK Total Diet Study (TDS) were measured and dietary exposures estimated. Composite samples for the 20 TDS food groups (bread, fish, fruit, etc.) were collected from 24 UK towns and analysed for their levels of aluminium, antimony, arsenic, barium, bismuth, cadmium, chromium, copper, germanium, indium, lead, manganese, mercury, molybdenum, nickel, palladium, platinum, rhodium, ruthenium, selenium, strontium, thallium, tin, and zinc. Concentrations of each of the elements in the food groups were lower than or similar to those reported in the previous TDS survey, conducted in 2000, with the exception of aluminium, barium, and manganese. Dietary exposures to the 24 elements were estimated for UK consumers and compared with previous estimates made over the last 30 years in order to examine any trends in exposure to these elements in the typical UK diet. Population exposures to the elements have generally declined over time, and exposures to most of these elements remain at low levels. The independent UK Government scientific Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT) commented on the estimated dietary exposures, taking into account their previous evaluations (in 2003 and 2008), and identified no major concerns for the health of consumers, but did advise that there was a need for more information on aluminium and barium, and also commented that dietary exposure to inorganic arsenic and to lead should continue to be reduced. PMID:20628929

  13. Toxicity of heavy metals and metal-containing nanoparticles on plants.

    PubMed

    Mustafa, Ghazala; Komatsu, Setsuko

    2016-08-01

    Plants are under the continual threat of changing climatic conditions that are associated with various types of abiotic stresses. In particular, heavy metal contamination is a major environmental concern that restricts plant growth. Plants absorb heavy metals along with essential elements from the soil and have evolved different strategies to cope with the accumulation of heavy metals. The use of proteomic techniques is an effective approach to investigate and identify the biological mechanisms and pathways affected by heavy metals and metal-containing nanoparticles. The present review focuses on recent advances and summarizes the results from proteomic studies aimed at understanding the response mechanisms of plants under heavy metal and metal-containing nanoparticle stress. Transport of heavy metal ions is regulated through the cell wall and plasma membrane and then sequestered in the vacuole. In addition, the role of different metal chelators involved in the detoxification and sequestration of heavy metals is critically reviewed, and changes in protein profiles of plants exposed to metal-containing nanoparticles are discussed in detail. Finally, strategies for gaining new insights into plant tolerance mechanisms to heavy metal and metal-containing nanoparticle stress are presented. This article is part of a Special Issue entitled: Plant Proteomics--a bridge between fundamental processes and crop production, edited by Dr. Hans-Peter Mock. PMID:26940747

  14. On the Navier-Stokes equations with constant total temperature

    NASA Technical Reports Server (NTRS)

    Gottlieb, D.; Gustafsson, B.

    1975-01-01

    For various applications in fluid dynamics, it is assumed that the total temperature is constant. Therefore, the energy equation can be replaced by an algebraic relation. The resulting set of equations in the inviscid case is analyzed. It is shown that the system is strictly hyperbolic and well posed for the initial value problems. Boundary conditions are described such that the linearized system is well posed. The Hopscotch method is investigated and numerical results are presented.

  15. Total Dose Effects on Error Rates in Linear Bipolar Systems

    NASA Technical Reports Server (NTRS)

    Buchner, Stephen; McMorrow, Dale; Bernard, Muriel; Roche, Nicholas; Dusseau, Laurent

    2007-01-01

    The shapes of single event transients in linear bipolar circuits are distorted by exposure to total ionizing dose radiation. Some transients become broader and others become narrower. Such distortions may affect SET system error rates in a radiation environment. If the transients are broadened by TID, the error rate could increase during the course of a mission, a possibility that has implications for hardness assurance.

  16. Total Syntheses of Isowondonins Based on a Biosynthetic Pathway.

    PubMed

    Yu, Shuai; Li, Feng; Jeon, Hongjun; Lee, Seokwoo; Shin, Jongheon; Kim, Sanghee

    2016-06-17

    The first total syntheses of (-)-isowondonin A and (-)-isowondonin B, which are unusual imidazole marine alkaloids, has been accomplished through the development of methods for the selective formation of styryl sulfate group and regioselective alkylation of the imidazole. Application of the Noyori asymmetric hydrogenation of ketones allows the asymmetric synthesis. These results in conjunction with ECD calculations led to the determination of the absolute configuration of isowondonins. PMID:27226031

  17. Metal-on-Metal Hip Arthroplasty: A Review of Adverse Reactions and Patient Management.

    PubMed

    Drummond, James; Tran, Phong; Fary, Camdon

    2015-01-01

    Recent alarming joint registry data highlighting increased revision rates has prompted further research into the area of metal-on-metal hip replacements and resurfacings. This review article examines the latest literature on the topic of adverse reactions to metal debris and summarises the most up-to-date guidelines on patient management. Adverse reactions to metal debris can cause significant damage to soft tissue and bone if not diagnosed early. Furthermore, not every patient with an adverse reaction to metal debris will be symptomatic. As such, clinicians must remain vigilant when assessing and investigating these patients in order to detect failing implants and initiate appropriate management. PMID:26132653

  18. Metal containing material processing on coater/developer system

    NASA Astrophysics Data System (ADS)

    Kawakami, Shinichiro; Mizunoura, Hiroshi; Matsunaga, Koichi; Hontake, Koichi; Nakamura, Hiroshi; Shimura, Satoru; Enomoto, Masashi

    2016-03-01

    Challenges of processing metal containing materials need to be addressed in order apply this technology to Behavior of metal containing materials on coater/developer processing including coating process, developer process and tool metal contamination is studied using CLEAN TRACKTM LITHIUS ProTM Z (Tokyo Electron Limited). Through this work, coating uniformity and coating film defectivity were studied. Metal containing material performance was comparable to conventional materials. Especially, new dispense system (NDS) demonstrated up to 80% reduction in coating defect for metal containing materials. As for processed wafer metal contamination, coated wafer metal contamination achieved less than 1.0E10 atoms/cm2 with 3 materials. After develop metal contamination also achieved less than 1.0E10 atoms/cm2 with 2 materials. Furthermore, through the metal defect study, metal residues and metal contamination were reduced by developer rinse optimization.

  19. ``Electric growth`` of metal overlayers on semiconductor substrates

    SciTech Connect

    Zhang, Z.; Cho, J.H. |; Niu, Q.; Shih, C.K.; Suo, Z.

    1998-02-01

    In this article, the authors present the main results from their recent studies of metal overlayer growth on semiconductor substrates. They show that a variety of novel phenomena can exist in such systems, resulting from several competing interactions. The confined motion of the conduction electrons within the metal overlayer can mediate a surprisingly long-range repulsive force between the metal-semiconductor interface and the growth front, acting to stabilize the overlayer. Electron transfer from the overlayer to the substrate leads to an attractive force between the two interfaces, acting to destabilize the overlayer. Interface-induced Friedel oscillations in electron density can further impose an oscillatory modulation onto the two previous interactions. These three competing factors, of all electronic nature, can make a flat metal overlayer critically, marginally, or magically stable, or totally unstable against roughening. The authors further show that, for many systems, these electronic effects can easily win over the effect of stress. First-principles studies of a few representative systems support the main features of the present electronic growth concept.

  20. Instabilities of structured metal films on nanoscale

    NASA Astrophysics Data System (ADS)

    Dong, Nanyi; Wu, Yueying; Fowlkes, Jason; Rack, Philip; Kondic, Lou

    2014-11-01

    We consider instabilities of metal films on nanoscale, with particular focus on the interplay between the initial geometry and instability development. In experiments, metal films are deposited lithographically, allowing for precise control of the initial shape, and then exposed to laser pulses that liquefy them. The considered geometries involve various shapes (cylinders or prisms) superimposed on top of a flat film. We consider this problem within the framework of the long wave (lubrication) theory. Our simulations show that the main features of the instability development could be captured, as long as destabilizing liquid-solid interaction is considered in the model. We conclude by discussing the influence of the distance between the imposed perturbations, their shape, as well as experimental noise on the evolution. Supported by NSF Grant No. CBET-1235710.

  1. Anharmonic Vibrational Spectroscopy on Metal Transition Complexes

    NASA Astrophysics Data System (ADS)

    Latouche, Camille; Bloino, Julien; Barone, Vincenzo

    2014-06-01

    Advances in hardware performance and the availability of efficient and reliable computational models have made possible the application of computational spectroscopy to ever larger molecular systems. The systematic interpretation of experimental data and the full characterization of complex molecules can then be facilitated. Focusing on vibrational spectroscopy, several approaches have been proposed to simulate spectra beyond the double harmonic approximation, so that more details become available. However, a routine use of such tools requires the preliminary definition of a valid protocol with the most appropriate combination of electronic structure and nuclear calculation models. Several benchmark of anharmonic calculations frequency have been realized on organic molecules. Nevertheless, benchmarks of organometallics or inorganic metal complexes at this level are strongly lacking despite the interest of these systems due to their strong emission and vibrational properties. Herein we report the benchmark study realized with anharmonic calculations on simple metal complexes, along with some pilot applications on systems of direct technological or biological interest.

  2. Growth morphology and properties of metals on graphene

    NASA Astrophysics Data System (ADS)

    Liu, Xiaojie; Han, Yong; Evans, James W.; Engstfeld, Albert K.; Behm, R. Juergen; Tringides, Michael C.; Hupalo, Myron; Lin, Hai-Qing; Huang, Li; Ho, Kai-Ming; Appy, David; Thiel, Patricia A.; Wang, Cai-Zhuang

    2015-12-01

    Graphene, a single atomic layer of graphite, has been the focus of recent intensive studies due to its novel electronic and structural properties. Metals grown on graphene also have been of interest because of their potential use as metal contacts in graphene devices, for spintronics applications, and for catalysis. All of these applications require good understanding and control of the metal growth morphology, which in part reflects the strength of the metal-graphene bond. Also of importance is whether the interaction between graphene and metal is sufficiently strong to modify the electronic structure of graphene. In this review, we will discuss recent experimental and computational studies related to deposition of metals on graphene supported on various substrates (SiC, SiO2, and hexagonal close-packed metal surfaces). Of specific interest are the metal-graphene interactions (adsorption energies and diffusion barriers of metal adatoms), and the crystal structures and thermal stability of the metal nanoclusters.

  3. Effects of historic metal(loid) pollution on earthworm communities.

    PubMed

    Lévêque, Thibaut; Capowiez, Yvan; Schreck, Eva; Mombo, Stéphane; Mazzia, Christophe; Foucault, Yann; Dumat, Camille

    2015-04-01

    The effects of metal(loid)s (Pb, Cd, Cu, Zn, As and Sb) from atmospheric fallout on earthworm communities were investigated in a fallow meadow located close to a 60-year-old lead recycling factory. We examined abundance and species diversity as well as the ratio of adult-to-juvenile earthworms, along five 140 m parallel transects. The influence of soil pollution on the earthworm community at the plot scale was put in context by measuring some physico-chemical soil characteristics (OM content, N content, pH), as well as total and bioavailable metal(loid) concentrations. Earthworms were absent in the highly polluted area (concentration from 30,000 to 5000 mg Pb·kg(-1) of dried soil), just near the factory (0-30 m area). A clear and almost linear relationship was observed between the proportion of juvenile versus mature earthworms and the pollution gradient, with a greater proportion of adults in the most polluted zones (only adult earthworms were observed from 30 to 50 m). Apporectodea longa was the main species present just near the smelter (80% of the earthworms were A. longa from 30 to 50 m). The earthworm density was found to increase progressively from five individuals·m(-2) at 30 m to 135 individuals·m(-2) at 140 m from the factory. On average, metal(loid) accumulation in earthworm tissues decreased linearly with distance from the factory. The concentration of exchangeable metal(loid)s in earthworm surface casts was higher than that of the overall soil. Finally, our field study clearly demonstrated that metal(loid) pollution has a direct impact on earthworm communities (abundance, diversity and proportion of juveniles) especially when Pb concentrations in soil were higher than 2050 mg·kg(-1). PMID:25616191

  4. New Insights into Wear and Biological Effects of Metal-on-Metal Bearings

    PubMed Central

    Catelas, Isabelle; Wimmer, Markus A.

    2011-01-01

    Background: Despite the renewed interest in metal-on-metal implants in the past two decades, the underlying wear mechanisms and biological effects are still not fully understood. Methods: This paper first reviews the tribology of metal-on-metal bearings, bringing new insights into the interaction of wear and corrosion, and putting the characteristics and the potential origin of wear particles in perspective with the proposed wear mechanisms. It then summarizes the current knowledge on the biological effects of particles and metal ions in relation to these wear mechanisms. Results: Tribochemical reactions play an important role in the wear of metal-on-metal joints. The generated tribomaterial, which progressively forms by mechanical mixing of the uppermost nanocrystalline zone of the metal surface with proteins from the synovial fluid, governs the wear rate and influences the corrosive behavior of the bearing. Nanometer-sized wear particles may initially originate from the passivation layer covering the implant surface and then detach from this tribolayer. The inflammatory response observed surrounding metal-on-metal implants appears to be lower than that around metal-on-polyethylene implants. However, metallic byproducts, which can complex with proteins, may lead to a T lymphocyte-mediated hypersensitivity response. Conclusions: The tribolayer appears to have beneficial effects on the wear rate. Much information has been gained on wear particle characteristics, but the exact mechanisms of particle detachment remain to be further elucidated. Excessive wear along with a hypersensitivity response may be at the origin of the early adverse tissue reactions that have been recently reported in some patients with metal-on-metal implants. Clinical Relevance: Future development of new methods to improve the tribolayer retention and optimize the tribocorrosive properties of the implant may minimize the clinical impact of implant wear and immune responses. PMID:21543694

  5. On designing room sheilding for total-body irradiation

    SciTech Connect

    Barish, R.J.

    1996-05-01

    When designing shielding for total-body irradiation as an additional modality of treatment in an ordinary radiation therapy room, the extended treatment distance used for these patients greatly increases the workload because of the inverse-square factor. In a seeming contradiction to logic, for a facility with an exterior wall in the path of one lateral primary beam, and a restricted area behind the other primary wall, the overall shielding requirements are lower if the TBI patients are treated with the machine oriented toward the occupied interior. 4 refs.

  6. Wall effects on the electrical manipulation of metal nanowires.

    PubMed

    Loucaides, Neophytos G; Ramos, Antonio

    2015-07-01

    The rotation induced by AC electric fields on metal nanowires has been studied theoretically and experimentally. In the experiments, the nanowires rotate close to the bottom of the device. The present work studies the effects of the wall on the electrorotation and electro-orientation of a metal nanowire numerically. The induced electrical rotation of a metal nanowire in solution is originated by both the electrical torque on the induced dipole and the induced charge EOF around the particle. The theoretical analysis presented here only considers the effects of the wall on the nanowire rotation originated by the torque on the induced dipole. Two methods are employed in the analysis in order to obtain the electrical and viscous torques acting on the nanowire: (i) the 3D electrical and hydrodynamic equations are simulated using the finite element method and (ii) hydrodynamic and electrical slender-body approximations are used to obtain, respectively, line distributions of Stokeslets and charge that take into account the proximity of a plane wall. The numerical results obtained from the two methods are totally in agreement. The main wall effects are that the electrical torque is reduced, the viscous torque is increased, and an electric repulsive force from the wall appears. PMID:25640250

  7. 'Total girlfriend experience': examining marketplace mythologies on sex tourism websites.

    PubMed

    Gezinski, Lindsay B; Karandikar, Sharvari; Levitt, Alexis; Ghaffarian, Roxane

    2016-07-01

    The purpose of this study was to conduct a systematic content analysis of sex tour websites to understand how sex tours are marketed to potential clients. A total of 380 web pages from 21 sex tour websites were reviewed. The sex tour websites sought to promote privacy and hassle-free travel with a local 'escort' and the opportunity for 'hooks-ups' with no strings attached. Three themes emerged around the description of sex workers: (1) enjoyment and complete acceptance, (2) a 'total girlfriend experience' and (3) exoticisation of the 'Third World' woman. The majority of the sex tourism websites used marketplace mythologies concerning racism, sexism and imperialism to appeal to sex tourists' desires for fantasy experiences, power and domination, and a renewed sense of identity. Legal and STI-related information was largely missing from the websites, and when it was included it was aimed at protecting sex tourists, not sex workers. It is of importance for researchers, social workers and others engaging with sex workers and sexscapes to recognise the power of language, cultural myths and framings and their ability to generate real-world social and health implications. PMID:26760690

  8. Some constructions on total labelling of m triangles

    NASA Astrophysics Data System (ADS)

    Voon, Chen Huey; Hui, Liew How; How, Yim Kheng

    2016-06-01

    Let mK3 = (Vm, Em) be a finite disconnected graph consisting of m disjoint triangles K3, where Vm is the set of vertices, Em is the set of edges and both Vm and Em are of the same size 3m. A total labelling of mK3 is a function f which maps the elements in Vm and Em to positive integer values, i.e. f : Vm ∪ Em → {1, 2, 3,...}. Let c be a positive integer. A triangle is said have a c-Erdo˝sian triangle labelling if it is a total labelling f : Vm ∪ Em → {c, c + 1, ..., c + 6m - 1} such that f (x) + f (y) = f (xy) for any x, y ∈ Vm and an edge xy ∈ Em joining them. In order to find all the c-Erdősian triangle labelling, a straightforward is to use the exhaustive search. However, the exhaustive search is only able to find c-Erdősian triangle labelling for m ≤ 5 due to combinatorial explosion. By studying the constant sum of vertex labels, we propose a strong permutation approach, which allows us to generate a certain classes of c-Erdősian triangle labelling up until m = 8.

  9. Organically Modified Silicas on Metal Nanowires

    PubMed Central

    2010-01-01

    Organically modified silica coatings were prepared on metal nanowires using a variety of silicon alkoxides with different functional groups (i.e., carboxyl groups, polyethylene oxide, cyano, dihydroimidazole, and hexyl linkers). Organically modified silicas were deposited onto the surface of 6-μm-long, ∼300-nm-wide, cylindrical metal nanowires in suspension by the hydrolysis and polycondensation of silicon alkoxides. Syntheses were performed at several ratios of tetraethoxysilane to an organically modified silicon alkoxide to incorporate desired functional groups into thin organosilica shells on the nanowires. These coatings were characterized using transmission electron microscopy, X-ray photoelectron spectroscopy, and infrared spectroscopy. All of the organically modified silicas prepared here were sufficiently porous to allow the removal of the metal nanowire cores by acid etching to form organically modified silica nanotubes. Additional functionality provided to the modified silicas as compared to unmodified silica prepared using only tetraethoxysilane precursors was demonstrated by chromate adsorption on imidazole-containing silicas and resistance to protein adsorption on polyethyleneoxide-containing silicas. Organically modified silica coatings on nanowires and other nano- and microparticles have potential application in fields such as biosensing or nanoscale therapeutics due to the enhanced properties of the silica coatings, for example, the prevention of biofouling. PMID:20715881

  10. The effect of the metal-on-metal hip controversy on Internet search activity.

    PubMed

    Phelan, Nigel; Kelly, John C; Moore, David P; Kenny, Patrick

    2014-10-01

    The recall of the articular surface replacement (ASR) hip prosthesis in 2010 represents one of the most controversial areas in orthopaedic surgery in recent years. The aim of this study was to compare the impact of the metal-on-metal hip controversy on Internet search activity in four different regions and determine whether the number of related news reports affected Internet search activity. The Google Trends, Keywords and News applications were used to record the number of news articles and Internet search activity for the terms "hip recall", "metal-on-metal hip" and "ASR hip" from October 2009 to October 2012 in the USA, the UK, Australia and Ireland. There was a large increase in search activity following the official recall in August 2010 in all countries. There was significantly greater search activity after the recall in Ireland compared with the UK for the search term "hip recall" (P = 0.004). For the term "metal-on-metal hip", the UK had significantly more search activity (P = 0.0009). There was a positive correlation between the number of news stories in UK and Ireland with Internet search activity but not in the USA or Australia. Differences between countries affected by the same recall highlight the complex effects of the media on public awareness. The data demonstrates a window of opportunity prior to the official recall for the development of an awareness campaign to provide patients with accurate information. PMID:24390041

  11. Demosaicking for multispectral images based on vectorial total variation

    NASA Astrophysics Data System (ADS)

    Shinoda, Kazuma; Hamasaki, Taisuke; Kawase, Maru; Hasegawa, Madoka; Kato, Shigeo

    2016-08-01

    Multispectral images (MSIs), which consist of more color components than RGB images, can be used in the field of vegetation analysis and medical imaging. A capturing system with multispectral filter array (MSFA) technology has been researched to shorten the capturing time and reduce the cost. In this system, the mosaicked image captured by the MSFA is demosaicked to reconstruct the MSI. We propose a demosaicking method using vectorial total variation (VTV) regularization for an MSI. This process is regarded as inverse problem of the image observation model. The reconstructed image is estimated by minimizing the VTV as a regularization term under the constraint condition. In the experimental results, the reconstructed image quality obtained using the proposed method is better than that of the conventional approaches in terms of both peak signal-to-noise ratio and structural similarity.

  12. Demosaicking for multispectral images based on vectorial total variation

    NASA Astrophysics Data System (ADS)

    Shinoda, Kazuma; Hamasaki, Taisuke; Kawase, Maru; Hasegawa, Madoka; Kato, Shigeo

    2016-05-01

    Multispectral images (MSIs), which consist of more color components than RGB images, can be used in the field of vegetation analysis and medical imaging. A capturing system with multispectral filter array (MSFA) technology has been researched to shorten the capturing time and reduce the cost. In this system, the mosaicked image captured by the MSFA is demosaicked to reconstruct the MSI. We propose a demosaicking method using vectorial total variation (VTV) regularization for an MSI. This process is regarded as inverse problem of the image observation model. The reconstructed image is estimated by minimizing the VTV as a regularization term under the constraint condition. In the experimental results, the reconstructed image quality obtained using the proposed method is better than that of the conventional approaches in terms of both peak signal-to-noise ratio and structural similarity.

  13. Total Dose Effects on Bipolar Integrated Circuits at Low Temperature

    NASA Technical Reports Server (NTRS)

    Johnston, A. H.; Swimm, R. T.; Thorbourn, D. O.

    2012-01-01

    Total dose damage in bipolar integrated circuits is investigated at low temperature, along with the temperature dependence of the electrical parameters of internal transistors. Bandgap narrowing causes the gain of npn transistors to decrease far more at low temperature compared to pnp transistors, due to the large difference in emitter doping concentration. When irradiations are done at temperatures of -140 deg C, no damage occurs until devices are warmed to temperatures above -50 deg C. After warm-up, subsequent cooling shows that damage is then present at low temperature. This can be explained by the very strong temperature dependence of dispersive transport in the continuous-time-random-walk model for hole transport. For linear integrated circuits, low temperature operation is affected by the strong temperature dependence of npn transistors along with the higher sensitivity of lateral and substrate pnp transistors to radiation damage.

  14. An Atomistic View on Fundamental Transport Processes on Metal Surfaces

    SciTech Connect

    Giesen, Margret

    2007-06-14

    In this lecture I present an introduction to the time-resolved observation of atomic transport processes on metal surfaces using scanning tunneling microscopy video sequences. The experimental data is analyzed using scaling law concepts known from statistical thermodynamics. I will present studies from metal surfaces in vacuum as well as in electrolyte.

  15. Effects of heavy metals on benthic macroinvertebrate communities in New Zealand streams

    SciTech Connect

    Hickey, C.W.; Clements, W.H.

    1998-11-01

    The authors performed chemical analyses of heavy metals in water and periphyton, toxicity tests with Daphnia magna and an indigenous mayfly (Deleatidium sp.), and field surveys of benthic macroinvertebrates to estimate the degree of metal pollution in three catchments in the Coromandel Peninsula of New Zealand. Good agreement was found between toxicity tests and measures of benthic community structure, particularly at stations with the highest metal levels. Responses of benthic communities at stations with low or moderate levels of metal contamination were variable and were probably confounded by factors other than heavy metals. Effects of heavy metals on benthic communities in New Zealand streams were similar to those reported for metal-polluted streams in North America and Europe, suggesting that responses to metal contamination are predictable. Abundance and species richness of mayflies, number of taxa in the orders Ephemeroptera, Plecoptera, and Trichoptera, and total taxonomic richness were the best indicators of heavy metals in New Zealand streams. In contrast, the quantitative macroinvertebrate community index (QMCI), a biotic index proposed for assessing effects of organic enrichment in New Zealand streams, could not distinguish between reference and metal-polluted streams. The poor performance of the QMCI was primarily due to incorrect tolerance scores for some taxa to heavy metals. Because of concerns regarding the subjective assignment of tolerance values to species, the authors recommend that tolerance values for dominant species in New Zealand streams should be verified experimentally in stream microcosms.

  16. On the shock response of cubic metals

    NASA Astrophysics Data System (ADS)

    Bourne, N. K.; Gray, G. T.; Millett, J. C. F.

    2009-11-01

    The response of four cubic metals to shock loading is reviewed in order to understand the effects of microstructure on continuum response. Experiments are described that link defect generation and storage mechanisms at the mesoscale to observations in the bulk. Four materials were reviewed; these were fcc nickel, the ordered fcc intermetallic Ni3Al, the bcc metal tantalum, and two alloys based on the intermetallic phase TiAl; Ti-46.5Al-2Cr-2Nb and Ti-48Al-2Cr-2Nb-1B. The experiments described are in two groups: first, equation of state and shear strength measurements using Manganin stress gauges and, second, postshock microstructural examinations and measurement of changes in mechanical properties. The behaviors described are linked through the description of time dependent plasticity mechanisms to the final states achieved. Recovered targets displayed dislocation microstructures illustrating processes active during the shock-loading process. Reloading of previously shock-prestrained samples illustrated shock strengthening for the fcc metals Ni and Ni3Al while showing no such effect for bcc Ta and for the intermetallic TiAl. This difference in effective shock hardening has been related, on the one hand, to the fact that bcc metals have fewer available slip systems that can operate than fcc crystals and to the observation that the lower symmetry materials (Ta and TiAl) both possess high Peierls stress and thus have higher resistances to defect motion in the lattice under shock-loading conditions. These behaviors, compared between these four materials, illustrate the role of defect generation, transport, storage, and interaction in determining the response of materials to shock prestraining.

  17. Massive failure of TiNbN coating in surface engineered metal-on-metal hip arthroplasty: Retrieval analysis.

    PubMed

    Łapaj, Łukasz; Markuszewski, Jacek; Wendland, Justyna; Mróz, Adrian; Wierusz-Kozłowska, Małgorzata

    2016-07-01

    This article presents examination of a failed total hip replacement with surface engineered metal-on-metal (MoM) articulation. The implant was coated with a thin TiNbN film (Physical Vapor Deposition), and at retrieval 53 months after implantation the coating was abraded on weight-bearing part of the head and acetabular component. Scanning electron microscopy of bearing surfaces demonstrated multifocal crack formation, delamination of small film fragments, and formation of aggregates containing nanometer sized wear debris. We also observed coating damage in third body mechanism. Complex failure mechanism of TiNbN coating demonstrated in this study suggests insufficient bonding strength between the coating and substrate alloy and raise concerns regarding the use of such coatings in total hip arthroplasty with MoM bearing. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1043-1049, 2016. PMID:25980456

  18. Progressive Cardiomyopathy in a Patient With Elevated Cobalt Ion Levels and Bilateral Metal-on-Metal Hip Arthroplasties.

    PubMed

    Mosier, Brian A; Maynard, Lance; Sotereanos, Nicholas G; Sewecke, Jeffrey J

    2016-01-01

    Systemic cobalt toxicity is a rare complication after metal-on-metal (MOM) total hip arthroplasty. Here we present a case of progressive cardiomyopathy, as evidenced by biopsy and cardiac magnetic resonance imaging (MRI), in a patient with bilateral MOM total hip arthroplasties. To our knowledge, it is one of the first cases in which cardiomyopathy resulting from systemic cobalt disease has been shown on MRI. While there is no guideline to unequivocally diagnose cobalt cardiomyopathy, the constellation of findings, including pathologic, biologic, blood levels, imaging, and surgical, all uniformly indicate a unifying diagnosis. The lack of improvement after removal of the prosthetic device supports a diagnosis of permanent myocardial damage, which is consistent with cardiomyopathy of advanced toxic etiology. PMID:26991580

  19. Metal ion effects on enolase activity

    SciTech Connect

    Lee, M.E.; Nowak, T.

    1986-05-01

    Most metal binding studies with yeast enolase suggest that two metals per monomer are required for catalytic activity. The functions of metal I and metal II have not been unequivocally defined. In a series of kinetic experiments where the concentration of MgII is kept constant at subsaturating levels (1mM), the addition of MnII or of ZnII gives a hyperbolic decrease in activity. The final velocity of these mixed metal systems is the same velocity obtained with either only MnII or ZnII respectively. The concentration of MnII (40 ..mu..M) or of Zn (2..mu..M) which gives half maximal effect in the presence of (1mM) MgII is approximately the same as the Km' value for MnII (9..mu..M) or ZnII (3..mu..M) respectively. Direct binding of MnII to enolase in the absence and presence of MgII shows that MnII and MgII compete for the same metal site on enolase. In the presence of 2-phosphoglycerate (2-PGA) and MgII, only a single site is occupied by MnII. Results suggest MnII at site I and MgII at site II. PRR and high resolution /sup 1/H and /sup 31/P NMR studies of enzyme-ligand complexes containing MnII and MgII and MnII are consistent with this model. /sub 31/P measurements allow a measure of the equilibrium constant (0.36) for enolase. Saturation transfer measurements yield net rate constants (k/sub f/ = 0.49s/sup -1/; k/sub r/ = 1.3s/sup -1/) for the overall reaction. These values are smaller than k/sub cat/ (38s/sup -1/) measured under analogous conditions. The cation at site I appears to determine catalytic activity.

  20. Gluteal muscle fatty atrophy is not associated with elevated blood metal ions or pseudotumors in patients with a unilateral metal-on-metal hip replacement

    PubMed Central

    Reito, Aleksi; Elo, Petra; Nieminen, Jyrki; Puolakka, Timo; Eskelinen, Antti

    2016-01-01

    Background and purpose There are no international guidelines to define adverse reaction to metal debris (ARMD). Muscle fatty atrophy has been reported to be common in patients with failing metal-on-metal (MoM) hip replacements. We assessed whether gluteal muscle fatty atrophy is associated with elevated blood metal ion levels and pseudotumors. Patients and methods 263 consecutive patients with unilateral ASR XL total hip replacement using a posterior approach and with an unoperated contralateral hip were included in the study. All patients had undergone a standard screening program at our institution, including MRI and blood metal ion measurement. Muscle fatty atrophy was graded as being absent, mild, moderate, or severe in each of the gluteal muscles. Results The prevalance of moderate-to-severe gluteal muscle atrophy was low (12% for gluteus minimus, 10% for gluteus medius, and 2% for gluteus maximus). Muscle atrophy was neither associated with elevated blood metal ion levels (> 5 ppb) nor with the presence of a clear (solid- or mixed-type) pseudotumor seen in MRI. A combination of moderate-to-severe atrophy in MRI, elevated blood metal ion levels, and MRI-confirmed mixed or solid pseudotumor was rare. Multivariable regression revealed that “preoperative diagnosis other than osteoarthrosis” was the strongest predictor of the presence of fatty atrophy. Interpretation Gluteal muscle atrophy may be a clinically significant finding with influence on hip muscle strength in patients with MoM hip replacement. However, our results suggest that gluteal muscle atrophy seen in MRI is not associated with either the presence or severity of ARMD, at least not in patients who have been operated on using the posterior approach. PMID:26427902

  1. Present and future perspectives on total artificial hearts

    PubMed Central

    Gerosa, Gino; Scuri, Silvia; Iop, Laura

    2014-01-01

    Due to shortages in donor organ availability, advanced heart-failure patients are at high risk of further decompensation and often death while awaiting transplantation. This shortage has led to the development of effective mechanical circulatory support (MCS). Currently, various implantable ventricular-assist devices (VADs) are able to provide temporary or long-term circulatory support for many end-stage heart-failure patients. Implantation of a total artificial heart (TAH) currently represents the surgical treatment option for patients requiring biventricular MCS as a bridge to transplant (BTT) or destination therapy (DT). However, the clinical applicability of available versions of positive displacement pumps is limited by their size and associated complications. Application of advanced technology is aimed at solving some of these issues, attempting to develop a new generation of smaller and more effective TAHs to suit a wider patient population. Particular targets for improvement include modifications to the biocompatibility of device designs and materials in order to decrease hemorrhagic and thromboembolic complications. Meanwhile, new systems to power implanted driving units which are fully operational without interruption of skin barriers represent a potential means of decreasing the risk of infections. In this review, we will discuss the history of the TAH, its development and clinical application, the implications of the existing technological solutions, published outcomes and the future outlook for TAHs. PMID:25512901

  2. Photoacoustic study on the possible components of total suspended particles

    NASA Astrophysics Data System (ADS)

    Wang, Xidong; Huang, Zuohua; Tang, Zhilie

    2006-02-01

    Total suspended particles (TSP) are one of the main atmospheric pollutants. The ingredients are very complex, mainly including black carbon (C),organic compound, inorganic compound and biologic component, which will do great harm to human's health. During environmental monitoring, the airborne suspended particle always is an index for evaluating the quality of atmosphere. In this article, possible mixture of TSP is proposed to determine its ingredients and content by photoacoustic spectroscopy. The normalized photoacoustic (PA) signal of the sulfur powder, mixtures of sulfur and black carbon in different proportions are obtained respectively. Simulation with linear equation says that the PA signal has a certain relationship with the content of sample. The normalized PA spectroscopy of various materials is acquired via examining the sample of the powder of cupric sulfate mixed with nitro compound (2, 5 -methoxybenzoic-4nitro-dehyde), Portland cement, residual particles of automobile exhaust pipe, ash of power plant's stocks. The experimental results have important reference value to the practical analysis of TSP, it also provides new possible methodology to the environmental monitoring.

  3. Present and future perspectives on total artificial hearts.

    PubMed

    Gerosa, Gino; Scuri, Silvia; Iop, Laura; Torregrossa, Gianluca

    2014-11-01

    Due to shortages in donor organ availability, advanced heart-failure patients are at high risk of further decompensation and often death while awaiting transplantation. This shortage has led to the development of effective mechanical circulatory support (MCS). Currently, various implantable ventricular-assist devices (VADs) are able to provide temporary or long-term circulatory support for many end-stage heart-failure patients. Implantation of a total artificial heart (TAH) currently represents the surgical treatment option for patients requiring biventricular MCS as a bridge to transplant (BTT) or destination therapy (DT). However, the clinical applicability of available versions of positive displacement pumps is limited by their size and associated complications. Application of advanced technology is aimed at solving some of these issues, attempting to develop a new generation of smaller and more effective TAHs to suit a wider patient population. Particular targets for improvement include modifications to the biocompatibility of device designs and materials in order to decrease hemorrhagic and thromboembolic complications. Meanwhile, new systems to power implanted driving units which are fully operational without interruption of skin barriers represent a potential means of decreasing the risk of infections. In this review, we will discuss the history of the TAH, its development and clinical application, the implications of the existing technological solutions, published outcomes and the future outlook for TAHs. PMID:25512901

  4. Does Ion Release Differ Between Hip Resurfacing and Metal-on-metal THA?

    PubMed Central

    Moroni, Antonio; Cadossi, Matteo; Baldini, Nicola; Giannini, Sandro

    2008-01-01

    Modern metal-on-metal hip resurfacing was introduced as a bone-preserving method of joint reconstruction for young and active patients; however, the large diameter of the bearing surfaces is of concern for potential increased metal ion release. We hypothesized there were no differences in serum concentrations of chromium, cobalt, and molybdenum between patients who had metal-on-metal hip resurfacing (Group A; average head diameter, 48 mm; median followup, 24 months) and patients who had 28-mm metal-on-metal THA (Group B; median followup, 25 months). Serum concentrations also were compared with concentrations in healthy subjects. We identified no differences in ion levels between Groups A and B. A distinction was made according to gender. Women showed a higher chromium release in Group A whereas men had a higher cobalt release in Group B. Values obtained from Group A were higher than those of the control subjects. Our data suggest metal-on-metal bearings for THA should not be rejected because of concern regarding potential increased metal ion release; however, patients with elevated ion levels, even without loosening or toxicity, could be at higher risk and should be followed up periodically. Level of Evidence: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence. PMID:18196364

  5. Thermodynamics of Metal Composites Based on Polyvinylchloride

    NASA Astrophysics Data System (ADS)

    Kolupaev, B. B.; Lyashuk, T. G.; Kolupaev, B. S.

    2014-03-01

    We present the results of experimental investigations of the thermodynamic properties of composites based on polyvinylchloride and copper nanoparticles obtained by electrical explosion of the conductor. It has been established that the thermodynamic potentials H and G in determining the system parameters (s, T, p, V) depend nonlinearly on the temperature and content of the filler. β- and α-relaxation transitions as a general phenomenon characteristic of the fluctuation structure of polyvinylchloride are observed thereby. The introduction of a nanodispersed metal filler into polyvinylchloride increases the amount of activation energy and the time of "settled" life of the structural elements, changing the thermodynamic stability of the composite.

  6. 13. Underside Span 1, Hot Metal Bridge on right toward ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. Underside Span 1, Hot Metal Bridge on right toward Pier 1. - Monongahela Connecting Railroad Company, Hot Metal Bridge, Spanning Monongahela River at mile post 3.1, Pittsburgh, Allegheny County, PA

  7. Effects of oral prazosin on total plasma digoxin levels.

    PubMed

    Copur, S; Tokgözoğlu, L; Oto, A; Oram, E; Uğurlu, S

    1988-01-01

    Prazosin and digoxin are frequently coadministered in clinical practice. To determine the effects of oral prazosin treatment on steady-state digoxin levels, 20 patients receiving a constant maintenance dose of digoxin, who had normal renal and liver functions and were not receiving any other treatment, were given 5 mg of prazosin for 3 days. Plasma digoxin levels were measured before, on days 1 and 3 of prazosin treatment, and after prazosin had been discontinued. It was found that prazosin significantly increased plasma digoxin levels. On discontinuation of prazosin digoxin levels returned to their previous values. PMID:3371837

  8. Gas adsorption on metal-organic frameworks

    DOEpatents

    Willis, Richard R.; Low, John J. , Faheem, Syed A.; Benin, Annabelle I.; Snurr, Randall Q.; Yazaydin, Ahmet Ozgur

    2012-07-24

    The present invention involves the use of certain metal organic frameworks that have been treated with water or another metal titrant in the storage of carbon dioxide. The capacity of these frameworks is significantly increased through this treatment.

  9. METHOD OF FORMING A PROTECTIVE COATING ON FERROUS METAL SURFACES

    DOEpatents

    Schweitzer, D.G.; Weeks, J.R.; Kammerer, O.F.; Gurinsky, D.H.

    1960-02-23

    A method is described of protecting ferrous metal surfaces from corrosive attack by liquid metals, such as liquid bismuth or lead-bismuth alloys. The nitrogen content of the ferrous metal surface is first reduced by reacting the metal surface with a metal which forms a stable nitride. Thereafter, the surface is contacted with liquid metal containing at least 2 ppm zirconium at a temperature in the range of 550 to 1100 deg C to form an adherent zirconium carbide layer on the ferrous surface.

  10. Shining light on metals in the environment

    SciTech Connect

    McNear, Jr., D.H.; Tappero, R.; Sparks, D.L.

    2010-07-20

    Elucidating the speciation of heavy metals in the environment is paramount to understanding their potential mobility and bioavailability. Cutting-edge synchrotron-based techniques such as microfocused X-ray absorption fine-structure (XAFS) and X-ray fluorescence (XRF) spectroscopy and microtomography have revolutionized the way metal reactions and processes in natural systems are studied. In this article, we apply these intense-light tools to decipher metal forms (species) and associations in contaminated soils and metal-hyperaccumulating plants.

  11. Voltage effects on cells cultured on metallic biomedical implants

    NASA Astrophysics Data System (ADS)

    Haerihosseini, Seyed Morteza

    voltage were measured and related to the observed responses. Results show that cathodic and anodic voltages outside the voltage viability range (-400 < V < +500) lead to primarily intrinsic apoptotic and necrotic cell death, respectively. Cell death is associated with cathodic current densities of 0.1 uAcm-2 and anodic current densities of 10 uAcm-2. Significant increase in metallic ions (Co, Cr, Ni, Mo) was seen at +500 mV, and -1000 mV (Cr only) compared to open circuit potential. The number and total projected area of adhesion complexes was also lower on the polarized alloy (p < 0.05). These results show that reduction reactions on CoCrMo alloys leads to apoptosis of cells on the surface and may be a relevant mode of cell death for metallic implants in-vivo. . On the other hand, we studied how surface oxide thickness of Ti affects its voltage viability range and cellular response and whether anodic oxidation can serve as a means to extend this range. Cellular behavior (cell viability, cytoskeletal organization, and cellular adhesion) on bare and anodized Ti samples, potentiostatically held at voltages at the cathodic edge of the viability range, were assessed. Surfaces were characterized using contact angle (CA) measurement technique and atomic force microscopy (AFM), and the observed cellular response was related to the changes in the electrochemical properties (electrochemical currents, open circuit potential, and impedance spectra) of the samples. Results show that anodization at a low voltage (9 V) in phosphate buffer saline (PBS) generates a compact surface oxide with comparable surface roughness and energy to the starting native oxide on the bare surface. The anodized surface extends the viability range at 24 hours by about a 100 mV in the cathodic region, and preserved the cytoskeletal integrity and cell adhesion. Broadening of the viability range corresponds to an increase in impedance of the anodized surface at -400 mV(Ag/AgCl) and the resulting low average

  12. Atmospheric deposition of heavy metals in Wuxi, China: estimation based on native moss analysis.

    PubMed

    Yan, Yun; Zhang, Qiang; Wang, G Geoff; Fang, Yan-Ming

    2016-06-01

    We studied atmospheric deposition of heavy metals in Wuxi, China, using moss (Haplocladium microphyllum and H. angustifolium) as a biomonitoring agent. Moss samples were collected from 49 sites determined by a systematic sampling method. The top layer of soil on each site was also sampled. No significant correlation (P < 0.05) was observed between the moss and soil concentrations for any of the six heavy metal elements (Cd, Cr, Cu, Ni, Pb, and Zn), indicating that the soil substrate had little effect on the heavy metal concentrations in the moss materials. The metal enrichment capacity of the moss material, characterized by the concentration ratio between the moss and soil samples for each heavy metal, was topped by Cd and then followed by Zn, Pb, Cu, Cr, and Ni, respectively. Significant (P < 0.05) correlations were found among the six elements in mosses, suggesting potential anthropogenic inputs of these heavy metal pollutants. Based on concentrations of the heavy metals in mosses and the calculated contamination factors, we evaluated the contamination level of each heavy metal on the 49 sampling sites. Spatial distribution maps of heavy metal deposition for each element were interpolated using ArcGIS 9.0. A total pollution coefficient was calculated for each sampling site to identify the seriously polluted areas in the region. PMID:27207630

  13. Alumina-on-alumina total hip prostheses in patients 40 years of age or younger.

    PubMed

    Bizot, P; Banallec, L; Sedel, L; Nizard, R

    2000-10-01

    To avoid the consequences of polyethylene wear in a high-risk population, 128 alumina-on-alumina total hip arthroplasties have been done in 104 consecutive patients. The maximum age of patients was 40 years. The main preoperative diagnoses were osteonecrosis and sequellae of congenital hip dislocation (71% of the hips). The same titanium alloy cemented stem was implanted in all of the hips. Four types of alumina acetabular component fixations were used: a cemented plain alumina socket (41 hips), a screw-in ring with an alumina insert (22 hips), a press-fit plain alumina socket (32 hips), and a press-fit titanium metal back with an alumina insert (33 hips). Eight patients (11 hips) died during the followup period. Sixteen revisions have been documented, 12 for acetabular aseptic loosening, three for bipolar loosening (two of which were septic), and one for unexplained pain. Eighty-eight hips in 74 patients have been followed up radiologically for 2 to 22 years. Wear was unmeasurable. Four additional sockets showed definite migration. The respective survival rates after 7 years were 94.1% for the cemented cup, 88.8% for the screw-in ring, 95.1% for cementless press-fit plain alumina socket and 94.3% for the metal-back press-fit component. The 10-year survival rate was 90.4% for the cemented socket and 88.8% for the screw-in ring. The 15-year survival rate was 78.9% for the cemented socket. Grafting was the only prognostic factor, with a survival rate of 62.6% after 10 years for the hips with a bone graft and of 90.1% for hips without a graft. The alumina-on-alumina bearing surfaces seem to be a valuable alternative to the standard metal-on-polyethylene system for young patients. However, an improvement in socket fixation is required to lengthen the life span of the prosthesis to match the life expectancy of this demanding population. PMID:11039794

  14. High temperature environmental effects on metals

    NASA Technical Reports Server (NTRS)

    Grisaffe, S. J.; Lowell, C. E.; Stearns, C. A.

    1977-01-01

    The gas turbine engine was used as an example to predict high temperature environmental attack on metals. Environmental attack in a gas turbine engine derives from high temperature, combustion products of the air and fuel burned, and impurities. Of all the modes of attack associated with impurity effects, hot corrosion was the most complicated mechanistically. Solutions to the hot corrosion problem were sought semi-empirically in: (1) improved alloys or ceramics; (2) protective surface coating; (3) use of additives to the engine environment; and (4) air/fuel cleanup to eliminate harmful impurities.

  15. Total dose dependency and ELDRS effects on bipolar linear devices

    NASA Technical Reports Server (NTRS)

    Yui, C. C.; McClure, S. S.; Rax, B. G.; Lehman, J. M.; Minto, T. D.; Wiedeman, M.

    2002-01-01

    The use of bipolar linear devices is prevalent in most satellite and some space applications. However, degradation as a result of low dose irradiations known as ELDERS (effects of enhanced low dose rate sensitivity) is a major concern when selecting flight hardware. Many studies and reports have been conducted on this possible phenomenon as well as their responsible physical mechanisms.

  16. Growth morphology and properties of metals on graphene

    SciTech Connect

    Liu, Xiaojie; Han, Yong; Evans, James W.; Engstfeld, Albert K.; Behm, R. Juergen; Tringides, Michael C.; Hupalo, Myron; Lin, Hai -Qing; Huang, Li; Ho, Kai -Ming; Appy, David; Thiel, Patricia A.; Wang, Cai -Zhuang

    2015-12-01

    Graphene, a single atomic layer of graphite, has been the focus of recent intensive studies due to its novel electronic and structural properties. With this study, metals grown on graphene also have been of interest because of their potential use as metal contacts in graphene devices, for spintronics applications, and for catalysis. All of these applications require good understanding and control of the metal growth morphology, which in part reflects the strength of the metal–graphene bond. The interaction between graphene and metal is sufficiently strong to modify the electronic structure of graphene is also of great importance. We will discuss recent experimental and computational studies related to deposition of metals on graphene supported on various substrates (SiC, SiO2, and hexagonal close-packed metal surfaces). Of specific interest are the metal–graphene interactions (adsorption energies and diffusion barriers of metal adatoms), and the crystal structures and thermal stability of the metal nanoclusters.

  17. Effects of heavy metals on earthworms along contamination gradients in organic rich soils.

    PubMed

    Lukkari, Tuomas; Taavitsainen, Mirka; Väisänen, Ari; Haimi, Jari

    2004-11-01

    Earthworm communities and metal (bio)availability to earthworms along contamination gradients was studied in order to support chemical analyses in risk assessment of metal contaminated soils. Earthworms were sampled in three metal contaminated areas with different habitat and soil properties in Finland. Earthworm and soil samples were collected at three distances (1, 2, and 4 km) from the emission sources. Earthworms were identified as to species and analyzed for heavy metals. Total soil metal concentrations were analyzed using an ultrasound-assisted extraction method and bioavailable metal fraction was estimated by acetic acid extraction. In two of the three areas studied, heavy metal concentrations close to the emission sources were high enough to have harmful effects on earthworms and their environments. In general, diversity, total numbers, and biomass of earthworms increased with increasing distance from the emission sources. When individuals were available for analyses close to the emission source, positive correlations between metal concentrations in the earthworms and those in the soils were observed. PMID:15388274

  18. Total x-ray power improvement on recent wire array experiments on the Z machine.

    SciTech Connect

    Jennings, Christopher A.; Ampleford, David J.; Porter, John Larry, Jr.; Cuneo, Michael Edward; Savage, Mark Edward; Rochau, Gregory Alan; Lopez, Mike R.; Jones, Brent Manley; Jones, Michael C.

    2010-11-01

    Recent experiments on the refurbished Z-machine were conducted using large diameter stainless steel arrays which produced x-ray powers of 260 TW. Follow-up experiments were then conducted utilizing tungsten wires with approximately the same total mass with the hypothesis that the total x-ray power would increase. On the large diameter tungsten experiments, the x-ray power averaged over 300 TW and the total x-ray energy was greater than 2MJ. Different analysis techniques for inferring the x-ray power will be described in detail.

  19. 7 CFR 1412.24 - Limitation of total base acreage on a farm.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 10 2011-01-01 2011-01-01 false Limitation of total base acreage on a farm. 1412.24... Base Acres for a Farm for Covered Commodities § 1412.24 Limitation of total base acreage on a farm. (a) The sum of the following must not exceed the total DCP cropland acreage on the farm, plus...

  20. Spectrophotometric total reducing sugars assay based on cupric reduction.

    PubMed

    Başkan, Kevser Sözgen; Tütem, Esma; Akyüz, Esin; Özen, Seda; Apak, Reşat

    2016-01-15

    As the concentration of reducing sugars (RS) is controlled by European legislation for certain specific food and beverages, a simple and sensitive spectrophotometric method for the determination of RS in various food products is proposed. The method is based on the reduction of Cu(II) to Cu(I) with reducing sugars in alkaline medium in the presence of 2,9-dimethyl-1,10-phenanthroline (neocuproine: Nc), followed by the formation of a colored Cu(I)-Nc charge-transfer complex. All simple sugars tested had the linear regression equations with almost equal slope values. The proposed method was successfully applied to fresh apple juice, commercial fruit juices, milk, honey and onion juice. Interference effect of phenolic compounds in plant samples was eliminated by a solid phase extraction (SPE) clean-up process. The method was proven to have higher sensitivity and precision than the widely used dinitrosalicylic acid (DNS) colorimetric method. PMID:26592591

  1. On estimating total daily evapotranspiration from remote surface temperature measurements

    NASA Technical Reports Server (NTRS)

    Carlson, Toby N.; Buffum, Martha J.

    1989-01-01

    A method for calculating daily evapotranspiration from the daily surface energy budget using remotely sensed surface temperature and several meteorological variables is presented. Vaules of the coefficients are determined from simulations with a one-dimensional boundary layer model with vegetation cover. Model constants are obtained for vegetation and bare soil at two air temperature and wind speed levels over a range of surface roughness and wind speeds. A different means of estimating the daily evapotranspiration based on the time rate of increase of surface temperature during the morning is also considered. Both the equations using our model-derived constants and field measurements are evaluated, and a discussion of sources of error in the use of the formulation is given.

  2. Effect of heavy metals on soil fungi

    NASA Astrophysics Data System (ADS)

    Sosak-Świderska, Bożena

    2010-05-01

    Fungi constitute a high proportion of the microbial biomass in soil.Being widespread in soil their large surface-to-volume ratio and high metabolic activity, fungi can contribute significantly to heavy metal dynamics in soil. At neutral pH heavy metals in soils tend to be immobilized to precipitation and/or absorption to cation exchange sites of clay minerals. In the acidic soils, metals are more mobile and enter food webs easier. Microbial production of acids and chelating agents can mobilize to toxic metals. Mobilization is often by uptake and intracellular accumulation of the heavy metlas, and in this way, the bioavailability of metals towards other organisms can be more reduced. Fungi were isolated from soils from Upper Silesia in Poland and belonged to widespread genera: Aspergillus, Cladosporium, Penicillium and Trichoderma. Fungi from different taxonomic groups differ greatly in their tolerance to heavy metals. This could be related to their wall structure and chemistry as well as biochemical and physiological characteristics of fungi. Localization of metals in fungal cells was studied using electron microscopy analysis. Metal biosorption in the cell wall can be complex as melanin granules. Fungal vacuoles have an important role in the regulation of the cytosolic concentration of metal ions, and may contribute to heavy metal tolerance.In polluted soils with heavy metals, fungal species composition can be changed and their physiological activity can be changed, too.

  3. Efficient waveguide coupler based on metal materials

    NASA Astrophysics Data System (ADS)

    Wu, Wenjun; Yang, Junbo; Chang, Shengli; Zhang, Jingjing; Lu, Huanyu

    2015-10-01

    Because of the diffraction limit of light, the scale of optical element stays in the order of wavelength, which makes the interface optics and nano-electronic components cannot be directly matched, thus the development of photonics technology encounters a bottleneck. In order to solve the problem that coupling of light into the subwavelength waveguide, this paper proposes a model of coupler based on metal materials. By using Surface Plasmon Polaritons (SPPs) wave, incident light can be efficiently coupled into waveguide of diameter less than 100 nm. This paper mainly aims at near infrared wave band, and tests a variety of the combination of metal materials, and by changing the structural parameters to get the maximum coupling efficiency. This structure splits the plane incident light with wavelength of 864 nm, the width of 600 nm into two uniform beams, and separately coupled into the waveguide layer whose width is only about 80 nm, and the highest coupling efficiency can reach above 95%. Using SPPs structure will be an effective method to break through the diffraction limit and implement photonics device high-performance miniaturization. We can further compress the light into small scale fiber or waveguide by using the metal coupler, and to save the space to hold more fiber or waveguide layer, so that we can greatly improve the capacity of optical communication. In addition, high-performance miniaturization of the optical transmission medium can improve the integration of optical devices, also provide a feasible solution for the photon computer research and development in the future.

  4. The effect of total hysterectomy on sexual function and depression

    PubMed Central

    Goktas, Sonay Baltaci; Gun, Ismet; Yildiz, Tulin; Sakar, Mehmet Nafi; Caglayan, Sabiha

    2015-01-01

    Background & Objectives: To investigate whether the operations of Type 1 hysterectomy and bilateral salpingo-oophorectomy performed for benign reasons have any effect on sexual life and levels of depression. Method: This is a multi-center, comparative, prospective study. Healthy, sexual active patients aged between 40 and 60 were included into the study. Data was collected with the technique of face-to-face meeting held three months before and after the operation by using the demographic data form developed by the researchers i.e. the Female Sexual Function Index (FSFI) and the Beck Depression Scale (BDS). Results: In the post-operative third month, there was an improvement in dysuria in terms of symptomatology (34% and 17%, P<0.001), while in FSFI (41.47±25.46 to 34.20±26.67, P<0.001) and BDS (12.87±11.19 to 14.27±10.95, P=0.015) there was a deterioration. For FSFI, 50-60 age range, extended family structure; and for BDS, educational status, not working and extended family structure were statistically important confounding factors for increased risk in the post-operative period. Conclusion: While hysterectomy and bilateral salpingo-oophorectomy performed for benign reasons brought about short-term improvement in urinary problems after the operation for sexually active and healthy women, they resulted in sexual dysfunction and increase in depression. The age, educational status, working condition and family structure is also important. PMID:26150871

  5. Graphene Growth on Low Carbon Solubility Metals

    NASA Astrophysics Data System (ADS)

    Wofford, Joseph Monroe

    Advances in synthesis are imperative if graphene is to fulfill its scientific and technological potential. Single crystal graphene of is currently available only in the small flakes generated by mechanical exfoliation. Layers of larger size may be grown either by the thermal decomposition of SiC or by chemical vapor deposition on metals. However, as they are currently implemented, these methods yield graphene films of inferior quality. Thus the requirement for wafer-scale, high-quality graphene films remains unmet. This dissertation addresses this issue by examining graphene growth on metal surfaces. Through a survey of the fundamental underlying processes, it provides guidance for improving the quality of the resulting graphene films. Graphene was grown on Cu(100), Cu(111), and Au(111) by physical vapor deposition of elemental C. The nucleation and growth behaviors of graphene were evaluated by low-energy electron microscopy. Graphene tends to nucleate heterogeneously at surface imperfections although it also does so homogeneously on Cu(111) and Au(111). Graphene growing on Cu(100) is governed by the attachment kinetics of C at the propagating crystal front. The resulting angularly dependent growth rate sculpts individual crystals into elongated lobes. In contrast, graphene growth on both Cu(111) and Au(111) is surface diffusion limited. This yields ramified, dendritic graphene islands. Graphene films grown on Cu(100) contain significant rotational disorder. This disorder is partially attributable to the symmetry mismatch between film and substrate. The common symmetry between graphene and Cu(111) contributes to a significant reduction in disorder in films grown on this surface. Most graphene domains occupy a ˜6º arc of orientations. On Au(111) the vast majority of graphene domains are locked into alignment with the substrate surface. The extraordinary extent of their orientational homogeneity is such that the resulting graphene film is a quasi-single crystal

  6. Ion irradiation effects on metallic nanocrystals

    NASA Astrophysics Data System (ADS)

    Kluth, P.; Johannessen, B.; Giulian, R.; Schnohr, C. S.; Foran, G. J.; Cookson, D. J.; Byrne, A. P.; Ridgway, M. C.

    We have investigated structural and morphological properties of metallic nanocrystals (NCs) exposed to ion irradiation. NCs were characterized by transmission electron microscopy in combination with advanced synchrotron-based analytical techniques, in particular X-ray absorption spectroscopy and small-angle X-ray scattering. A number of different effects were observed depending on the irradiation conditions. At energies where nuclear stopping is predominant, structural disorder/amorphization followed by inverse Ostwald ripening/dissolution due to ion beam mixing was observed for Au and Cu NCs embedded in SiO2. The ion-irradiation-induced crystalline to amorphous transition in the NCs, which cannot be achieved in the corresponding bulk metals, was attributed to their initially higher structural energy as compared to bulk material and possibly preferential nucleation of the amorphous phase at the NC/SiO2 interface. At very high irradiation energies (swift heavy ion irradiation), where the energy loss is nearly entirely due to electronic stopping, a size-dependent shape transformation of the NCs from spheres to rod like shapes was apparent in Au NCs. Our preliminary results are in good agreement with considerations on melting of the NCs in the ion track as one mechanism involved in the shape transformation.

  7. Notes on properties of holographic strange metals

    SciTech Connect

    Lee, Bum-Hoon; Pang, Da-Wei

    2010-11-15

    We investigate properties of holographic strange metals in p+2 dimensions, generalizing the analysis performed in [S. A. Hartnoll et al. J. High Energy Phys. 04 (2010) 120]. The bulk spacetime is a p+2-dimensional Lifshitz black hole, while the role of charge carriers is played by probe D-branes. We mainly focus on massless charge carriers, where most of the results can be obtained analytically. We obtain exact results for the free energy and calculate the entropy density and the heat capacity, as well as the speed of sound at low temperature. We obtain the DC conductivity and DC Hall conductivity and find that the DC conductivity takes a universal form in the large density limit, while the Hall conductivity is also universal in all dimensions. We also study the resistivity in different limits and clarify the condition for the linear dependence on the temperature, which is a key feature of strange metals. We show that our results for the DC conductivity are consistent with those obtained via the Kubo formula and we obtain the charge diffusion constant analytically. The corresponding properties of massive charge carriers are also discussed in brief.

  8. Notes on properties of holographic strange metals

    NASA Astrophysics Data System (ADS)

    Lee, Bum-Hoon; Pang, Da-Wei

    2010-11-01

    We investigate properties of holographic strange metals in p+2 dimensions, generalizing the analysis performed in [S. A. Hartnoll J. High Energy Phys.JHEPFG1029-8479 04 (2010) 120]. The bulk spacetime is a p+2-dimensional Lifshitz black hole, while the role of charge carriers is played by probe D-branes. We mainly focus on massless charge carriers, where most of the results can be obtained analytically. We obtain exact results for the free energy and calculate the entropy density and the heat capacity, as well as the speed of sound at low temperature. We obtain the DC conductivity and DC Hall conductivity and find that the DC conductivity takes a universal form in the large density limit, while the Hall conductivity is also universal in all dimensions. We also study the resistivity in different limits and clarify the condition for the linear dependence on the temperature, which is a key feature of strange metals. We show that our results for the DC conductivity are consistent with those obtained via the Kubo formula and we obtain the charge diffusion constant analytically. The corresponding properties of massive charge carriers are also discussed in brief.

  9. Ion irradiation effects on metallic nanocrystals

    SciTech Connect

    Kluth, P.; Johannessen, B.; Giulian, R.; Schnohr, C.S.; Foran, G.J.; Cookson, D.J.; Byrne, A.P.; Ridgway, M.C.

    2008-04-02

    We have investigated structural and morphological properties of metallic nanocrystals (NCs) exposed to ion irradiation. NCs were characterized by transmission electron microscopy in combination with advanced synchrotron-based analytical techniques, in particular X-ray absorption spectroscopy and small-angle X-ray scattering. A number of different effects were observed depending on the irradiation conditions. At energies where nuclear stopping is predominant, structural disorder/amorphization followed by inverse Ostwald ripening/dissolution due to ion beam mixing was observed for Au and Cu NCs embedded in SiO{sub 2}. The ion-irradiation-induced crystalline to amorphous transition in the NCs, which cannot be achieved in the corresponding bulk metals, was attributed to their initially higher structural energy as compared to bulk material and possibly preferential nucleation of the amorphous phase at the NC/SiO{sub 2} interface. At very high irradiation energies (swift heavy ion irradiation), where the energy loss is nearly entirely due to electronic stopping, a size-dependent shape transformation of the NCs from spheres to rod like shapes was apparent in Au NCs. Our preliminary results are in good agreement with considerations on melting of the NCs in the ion track as one mechanism involved in the shape transformation.

  10. Minor heavy metal: A review on occupational and environmental intoxication

    PubMed Central

    Wiwanitkit, Viroj

    2008-01-01

    Heavy metal is widely used in industries and presents as a problematic environmental pollution. Some heavy metals, especially lead and mercury, are well described for their occupational and environmental intoxication whereas the other minor heavy metals are less concerned. In this article, the author will present the details of occupational and environmental minor heavy metal intoxication. This review focuses mainly on aluminum, tin, copper, manganese, chromium, cadmium and nickel. PMID:20040969

  11. In vivo response of heme-oxygenase-1 to metal ions released from metal-on-metal hip prostheses.

    PubMed

    Beraudi, Alina; Bianconi, Eva; Catalani, Simona; Canaider, Silvia; De Pasquale, Dalila; Apostoli, Pietro; Bordini, Barbara; Stea, Susanna; Toni, Aldo; Facchin, Federica

    2016-07-01

    Metal ion release and accumulation is considered to be a factor responsible for the high failure rates of metal-on-metal (MoM) hip implants. Numerous studies have associated the presence of these ions, besides other factors, including a hypoxia‑like response and changes in pH due to metal corrosion leading to the induction of the oxidative stress response. The aim of the present study was to verify whether, in patients with a MoM hip prosthesis, mRNA and protein expression of HMOX‑1 was modulated by the presence of metal ions and whether patients without prostheses exhibit a different expression pattern of this enzyme. The study was conducted on 22 matched pairs of patients with and without prostheses, for a total of 44 samples. Ion dosage was determined using inductively coupled plasma mass spectrometry equipped with dynamic cell reaction. HMOX‑1 gene expression was quantified by reverse transcription-quantitative polymerase chain reaction and HMOX‑1 protein expression was analyzed using an enzyme-linked immunosorbent assay. The results demonstrated that although there were significant differences in the metallic ion concentrations amongst the two groups of patients, there was no correlation between circulating levels of cobalt (Co) and chromium (Cr), and HMOX‑1 gene and protein expression. Additionally, there was no significant difference in the protein expression levels of HMOX‑1 between the two groups. In conclusion, it was demonstrated that circulating Co and Cr ions released by articular prosthetics do not induce an increase in HMOX‑1 mRNA and protein expression at least 3.5 years after the implant insertion. The present study suggests that involvement of HMOX‑1 may be excluded from future studies and suggests that other antioxidant enzymes, including superoxide dismutase, glutathione peroxidase and reductase should be investigated. PMID:27176599

  12. Dermal exposure of Eisenia andrei earthworms: Effects of heavy metals on metallothionein and phytochelatin synthase gene expressions in coelomocytes.

    PubMed

    Homa, Joanna; Rorat, Agnieszka; Kruk, Jerzy; Cocquerelle, Claude; Plytycz, Barbara; Vandenbulcke, Franck

    2015-06-01

    Parameters such as total number of coelomocytes, riboflavin content in coelomocytes, expression of genes implied in metal homeostasis, and detoxification mechanisms can be used as biomarkers to assess the impact of metals on annelids. Defense biomarkers (detoxification gene expressions and coelomocyte parameters) were investigated in the ecotoxicologically important species Eisenia andrei following in vivo exposure to 5 different metals (zinc, copper, nickel, lead, and cadmium) at known concentrations. Coelomocyte numbers and riboflavin content were not affected by metallic exposure, but metal-specific gene expression variations were evidenced. PMID:25693738

  13. Copper metallization for on-chip interconnects

    NASA Astrophysics Data System (ADS)

    Gelatos, A. V.; Nguyen, Bich-Yen; Perry, Kathleen A.; Marsh, R.; Peschke, J.; Filipiak, Stanley M.; Travis, Edward O.; Thompson, Matthew A.; Saaranen, T.; Tobin, Phil J.; Mogab, C. J.

    1996-09-01

    Continued dimensional scaling of the elements of integrated circuits places significant restrictions on the width, density and current carrying capability of metallic interconnects. It is expected that, by the year 2000, the transistor channel length will be at 0.l8piri [1], while microprocessors will pack more than 15 million transistors over an area of '-700mm2. To conserve area, interconnects will continue to be stacked at an increasing number of levels (6 by the year 2000, vs 4 in todays leading microprocessors) and the minimum spacing and width within an interconnect layer will shrink to 0.3.tm. In addition, it is expected that future interconnects will need to sustain increasingly higher current densities without electromigration failures [2]. Aluminum alloys are the conductors of choice in present-day interconnects, and much effort is focused n means to extend the usefulness of aluminum through improvements in reliability, either by new alloy formulations [3], or by the development of complicated multimetal stacks [4. A more radical approach, which is gaining increased attention, is the replacement of aluminum altogether by copper. The bulk resistivity of copper is significantly lower than that of aluminum (1.7.tW-cm for Cu vs. 3.0iW-cm for Al-Cu), which is expected to translate to interconnects of higher performance because of reduction in signal propagation delay. In addition, the significantly higher melting temperature of copper (.-1100°C vs. -600°C for Al-Cu alloys) and its higher atomic weight are expected to translate to improved resistance to electromigration [5]. However, as with any new process trying to break into the mainstream, significant improvement in reliability and performance over that achievable with aluminum alloys must be demonstrated first. Towards this purpose, processes need to be developed that deposit conformal copper films of high purity with acceptable throughput, and integration schemes need to be developed which produce

  14. Effect of ferrous metal presence on lead leaching in municipal waste incineration bottom ashes.

    PubMed

    Oehmig, Wesley N; Roessler, Justin G; Zhang, Jianye; Townsend, Timothy G

    2015-01-01

    The recovery of ferrous and non-ferrous metals from waste to energy (WTE) ash continues to advance as the sale of removed metals improves the economics of waste combustion. Published literature suggests that Fe and Fe oxides play a role in suppressing Pb leaching in the Toxicity Characteristic Leaching Procedure (TCLP); further removal of ferrous metals from WTE ashes may facilitate higher Pb leaching under the TCLP. Eight WTE bottom ash size-fractions, from three facilities, were evaluated to assess the effect of metallic Fe addition and ferrous metal removal on TCLP leaching. Metallic Fe addition was demonstrated to reduce Pb leaching; the removal of ferrous metals by magnet resulted in a decrease in total available Pb (mg/kg) in most ash samples, yet Pb leachability increased in 5 of 6 ash samples. The research points to two chemical mechanisms to explain these results: redox interactions between Pb and Fe and the sorption of soluble Pb onto Fe oxide surfaces, as well as the effect of the leachate pH before and after metals recovery. The findings presented here indicate that generators, processors, and regulators of ash should be aware of the impact ferrous metal removal may have on Pb leaching, as a substantial increase in leaching may have significant implications regarding the management of WTE ashes. PMID:25464288

  15. Influence of different organic amendments on the potential availability of metals from soil: a study on metal fractionation and extraction kinetics by EDTA.

    PubMed

    Santos, Sérgio; Costa, Carina A E; Duarte, Armando C; Scherer, Heinrich W; Schneider, Rudolf J; Esteves, Valdemar I; Santos, Eduarda B H

    2010-01-01

    The effects of long-term application of different organic amendments, as compared to mineral fertilizer, on Zn, Cu and Pb content and leachability in a luvisol derived from loess were assessed. The organic fertilizers, applied since 1962, were compost (COM) - from green organic household waste, sewage sludge (SLU) - from municipal water treatment facilities, farmyard manure (FYM) and the doses applied since 1997 were 90tha(-1), 10tha(-1) and 9tha(-1), once in 3years, respectively. The kinetics of metals extraction with 0.05moldm(-3) EDTA at pH 6.0 has been studied. The two first-order reactions model was fitted to the kinetic data and allowed to distinguish two pools for each metal: a "labile" fraction (Q(1)), quickly extracted with a rate constant k(1), and a "moderately labile" fraction (Q(2)), more slowly extracted, with a rate constant k(2). Simultaneously, the pseudo-total metal contents in the soil samples were determined after digestion with aqua regia (3:1 HCl+HNO(3)). The obtained parameters Q(1), k(1), Q(2), k(2), for the kinetics of extraction of each metal in the three replicates of each fertilization mode, as well as the pseudo-total metal contents, were statistically analysed. COM and SLU application resulted in an increase of the total contents of Pb, Zn and Cu in soil. Further, the percentage of labile Zn and Pb also increased in consequence of the application of those amendments, particularly COM. The increase was more noticeable for Zn. FYM, despite not increasing the total content of Pb, Zn or Cu, did also have an effect on the leachability of Zn and Pb, increasing their labile fraction in soil. These results point to a potential risk of increasing metals mobility in soil, mainly Zn, associated to the use of organic amendments, particularly COM or SLU. PMID:19962175

  16. Depuration effects on trace metals in Anomalocardia brasiliana (Gmelin, 1791)

    SciTech Connect

    Wallner-Kersanach, M. ); Lobo, S.E.; Silva, E.M. da )

    1994-06-01

    Bivalves have been regarded as suitable bioindicators of metal pollution in the marine and estuarine environments. However, the metal concentrations of the soft parts of individual bivalves can vary considerably depending on size variations, geographic and genetic differences, individual variability in metal uptake, ingestion of sediment particles and induction of metal-binding proteins. Metal-containing particulate matter in the gut can also be significant. These authors showed that if deputation is not carried out, then large variations in metal concentrations are more likely to occur. In the Todos os Santos Bay on the northeastern coast of Brazil, the cockle A. brasiliana is the most abundant bivalve and is well adapted to area conditions. An important source of food for many local communities, this species has been frequently used as an indicator for heavy metals pollution; however, no data have been published on metal concentrations of A. brasiliana of different size classes and on the effects of deputation on overall concentration. It is therefore important to determine the metal concentrations in A. brasiliana both from the point of view of how the concentrations relate to metal loading of the area. The effect of size upon metal concentration of shellfish has been examined by Boyden, who found that zinc in Mytilus edulis was greater in smaller individuals while cadmium was independent of size. The objective of this study was to determine concentrations of copper, zinc, cadmium and lead in A. brasiliana collected from a site with a relatively low impact of heavy metal contamination, to examine metals in different size classes and to assess the effect of depuration on tissue concentration of the metals. These elements were selected due to their toxicity to marine organisms, when their excess as free metal may interact with cell structures and/or enzymes affecting metabolic activities. 22 refs., 2 figs., 2 tabs.

  17. Dependence of metal-enhanced fluorescence on surface roughness

    NASA Astrophysics Data System (ADS)

    François, Alexandre; Sciacca, Beniamino; Zuber, Agnieszka; Klantsataya, Elizaveta; Monro, Tanya M.

    2014-03-01

    Metal Enhanced Fluorescence (MEF) takes advantage of the coupling between surface plasmons, in either a metallic thin film or metallic nanoparticles, and fluorophores located in proximity of the metal, yielding an increase of the fluorophore emission. While MEF has been widely studied on metallic nanoparticles with the emphasis on creating brighter fluorescent labels, planar surfaces have not benefitted from the same attention. Here we investigate the influence of the surface roughness of a thin metallic film on the fluorescence enhancement. 50nm thick silver films were deposited on glass slides using either thermal evaporation with different evaporation currents or an electroless plating method based on the Tollens reaction to vary the surface roughness. Multiple layers of positively and negatively charged polyelectrolytes were deposited on top of the metallic coating to map out the enhancement factor as function of the gap between the metallic coating and fluorophore molecules covalently bound to the last polyelectrolyte layer. We show that fluorescence is enhanced by the presence of the metallic film, and in particular that the enhancement increases by a factor 3 to 40 for roughness ranging from 3 nm to 8 nm. Although these enhancement factors are modest compared to the enhancement produced by complex metallic nanoparticles or nano-patterned metallic thin films, the thin films used here are capable of supporting a plasmonic wave and offer the possibility of combining different techniques, such as surface plasmon resonance (with its higher refractive index sensitivity compared to localized plasmons) and MEF within a single device.

  18. Carbon Nanotube Patterning on a Metal Substrate

    NASA Technical Reports Server (NTRS)

    Nguyen, Cattien V. (Inventor)

    2016-01-01

    A CNT electron source, a method of manufacturing a CNT electron source, and a solar cell utilizing a CNT patterned sculptured substrate are disclosed. Embodiments utilize a metal substrate which enables CNTs to be grown directly from the substrate. An inhibitor may be applied to the metal substrate to inhibit growth of CNTs from the metal substrate. The inhibitor may be precisely applied to the metal substrate in any pattern, thereby enabling the positioning of the CNT groupings to be more precisely controlled. The surface roughness of the metal substrate may be varied to control the density of the CNTs within each CNT grouping. Further, an absorber layer and an acceptor layer may be applied to the CNT electron source to form a solar cell, where a voltage potential may be generated between the acceptor layer and the metal substrate in response to sunlight exposure.

  19. Chemical Sensors Based on Metal Oxide Nanostructures

    NASA Technical Reports Server (NTRS)

    Hunter, Gary W.; Xu, Jennifer C.; Evans, Laura J.; VanderWal, Randy L.; Berger, Gordon M.; Kulis, Mike J.; Liu, Chung-Chiun

    2006-01-01

    This paper is an overview of sensor development based on metal oxide nanostructures. While nanostructures such as nanorods show significan t potential as enabling materials for chemical sensors, a number of s ignificant technical challenges remain. The major issues addressed in this work revolve around the ability to make workable sensors. This paper discusses efforts to address three technical barriers related t o the application of nanostructures into sensor systems: 1) Improving contact of the nanostructured materials with electrodes in a microse nsor structure; 2) Controling nanostructure crystallinity to allow co ntrol of the detection mechanism; and 3) Widening the range of gases that can be detected by using different nanostructured materials. It is concluded that while this work demonstrates useful tools for furt her development, these are just the beginning steps towards realizati on of repeatable, controlled sensor systems using oxide based nanostr uctures.

  20. Electron impinging on metallic thin film targets

    NASA Astrophysics Data System (ADS)

    Rouabah, Z.; Bouarissa, N.; Champion, C.

    2010-03-01

    Based on the Vicanek and Urbassek theory [M. Vicanek, H.M. Urbassek, Phys. Rev. B 44 (1991) 7234] combined to a home-made Monte Carlo simulation, the present work deals with backscattering coefficients, mean penetration depths and stopping profiles for 1-4 keV electrons normally incident impinging on Al and Cu thin film targets. The cross-sections used to describe the electron transport are calculated via the appropriate analytical expression given by Jablonski [A. Jablonski, Phys. Rev. B 58 (1998) 16470] whose new improved version has been recently given [Z. Rouabah, N. Bouarissa, C. Champion, N. Bouaouadja, Appl. Surf. Sci. 255 (2009) 6217]. The behavior of the backscattering coefficient, mean penetration depth and stopping profiles versus the metallic film thickness at the nanometric scale and beyond is here analyzed and discussed.

  1. DEPOSITION OF METAL ON NONMETAL FILAMENT

    DOEpatents

    Magel, T.T.

    1959-02-10

    A method is described for purifying metallic uranium by passing a halogen vapor continuously over the impure uranium to form uranium halide vapor and immediately passing the halide vapor into contact with a nonmetallic refractory surface which is at a temperature above the melting point of uranium metal. The halide is decomposed at the heated surface depositing molten metal, which collects and falls into a receiver below.

  2. Effect of organic carbon and metal accumulation on the bacterial communities in sulphidogenic sediments.

    PubMed

    Bueche, Matthieu; Junier, Pilar

    2016-06-01

    A unique geochemical setting in Lake Cadagno, Switzerland, has led to the accumulation of insoluble metal sulphides in the sedimentary record as the result of past airborne pollution. This offers an exceptional opportunity to study the effect of these metals on the bacterial communities in sediments, and in particular to investigate further the link between metal contamination and an increase in the populations of endospore-forming bacteria observed previously in other metal-contaminated sediments. A decrease in organic carbon and total bacterial counts was correlated with an increase in the numbers of endospores in the oldest sediment samples, showing the first environmental evidence of a decrease in nutrient availability as a trigger of sporulation. Proteobacteria and Firmicutes were the two dominant bacterial phyla throughout the sediment, the former in an area with high sulphidogenic activity, and the latter in the oldest samples. Even though the dominant Firmicutes taxa were stable along the sediment core and did not vary with changes in metal contamination, the prevalence of some molecular species like Clostridium sp. was positively correlated with metal sulphide concentration. However, this cannot be generalized to all endospore-forming species. Overall, the community composition supports the hypothesis of sporulation as the main mechanism explaining the dominance of endospore formers in the deepest part of the sediment core, while metal contamination in the form of insoluble metal sulphide deposits appears not to be linked with sporulation as a mechanism of metal tolerance in this sulphidogenic ecosystem. PMID:26780045

  3. Metal-on-Metal Hip Prostheses and Systemic Health: A Cross-Sectional Association Study 8 Years after Implantation

    PubMed Central

    Prentice, Jennifer R.; Clark, Matthew J.; Hoggard, Nigel; Morton, Allison C.; Tooth, Claire; Paley, Martyn N.; Stockley, Ian; Hadjivassiliou, Marios; Wilkinson, J. Mark

    2013-01-01

    There is public concern over the long term systemic health effects of metal released from hip replacement prostheses that use large-diameter metal-on-metal bearings. However, to date there has been no systematic study to determine which organs may be at risk, or the magnitude of any effect. We undertook a detailed cross-sectional health screen at a mean of 8 years after surgery in 35 asymptomatic patients who had previously received a metal-on-metal hip resurfacing (MoMHR) versus 35 individually age and sex matched asymptomatic patients who had received a conventional hip replacement. Total body bone mineral density was 5% higher (mean difference 0.05 g/cm2, P = 0.02) and bone turnover was 14% lower (TRAP 5b, mean difference −0.56IU/L, P = 0.006; osteocalcin, mean difference −3.08 ng/mL, P = 0.03) in the hip resurfacing versus conventional hip replacement group. Cardiac ejection fraction was 7% lower (mean absolute difference −5%, P = 0.04) and left ventricular end-diastolic diameter was 6% larger (mean difference 2.7 mm, P = 0.007) in the hip resurfacing group versus those patients who received a conventional hip replacement. The urinary fractional excretion of metal was low (cobalt 5%, chromium 1.5%) in patients with MoMHR, but creatinine clearance was normal. Diuretic prescription was associated with a 40% increase in the fractional excretion of chromium (mean difference 0.5%, P = 0.03). There was no evidence of difference in neuropsychological, renal tubular, hepatic or endocrine function between groups (P>0.05). Our findings of differences in bone and cardiac function between patient groups suggest that chronic exposure to low elevated metal concentrations in patients with well-functioning MoMHR prostheses may have systemic effects. Long-term epidemiological studies in patients with well-functioning metal on metal hip prostheses should include musculoskeletal and cardiac endpoints to quantitate the risk of clinical disease. PMID

  4. Selective Metal-vapor Deposition on Organic Surfaces.

    PubMed

    Tsujioka, Tsuyoshi

    2016-02-01

    Selective metal-vapor deposition signifies that metal-vapor atoms are deposited on a hard organic surface, but not on a soft (low glass transition temperature, low Tg ) surface. In this paper, we introduce the origin, extension, and applications of selective metal-vapor deposition. An amorphous photochromic diarylethene film shows light-controlled selective metal-vapor deposition, which is caused by a large Tg change based on photoisomerization, but various organic surfaces, including organic crystal and polymers, can be utilized for achieving selective metal-vapor deposition. Various applications of selective metal-vapor deposition, including cathode patterning of organic light-emitting devices, micro-thin-film fuses, multifunctional diffraction gratings, in-plane electrical bistability for memory devices, and metal-vapor integration, have been demonstrated. PMID:26663735

  5. Studies on the optimization of deformation processed metal metal matrix composites

    SciTech Connect

    Ellis, T.W.

    1994-01-04

    A methodology for the production of deformation processed metal metal matrix composites from hyper-eutectic copper-chromium alloys was developed. This methodology was derived from a basic study of the precipitation phenomena in these alloys encompassing evaluation of microstructural, electrical, and mechanical properties. The methodology developed produces material with a superior combination of electrical and mechanical properties compared to those presently available in commercial alloys. New and novel alloying procedures were investigated to extend the range of production methods available for these material. These studies focused on the use of High Pressure Gas Atomization and the development of new containment technologies for the liquid alloy. This allowed the production of alloys with a much more refined starting microstructure and lower contamination than available by other methods. The knowledge gained in the previous studies was used to develop two completely new families of deformation processed metal metal matrix composites. These composites are based on immissible alloys with yttrium and magnesium matrices and refractory metal reinforcement. This work extends the physical property range available in deformation processed metal metal matrix composites. Additionally, it also represents new ways to apply these metals in engineering applications.

  6. High-Resolution Neutron Total and Capture Cross-Section Measurements on 206Pb

    SciTech Connect

    Borella, A.; Brusegan, A.; Siegler, P.; Schillebeeckx, P.; Moxon, M.C.; Aerts, G.; Gunsing, F.

    2005-05-24

    High-resolution neutron total and capture cross-section measurements have been performed on a 99.82% enriched 206Pb metallic sample. The transmission and capture measurements were carried out at the 25- and 60-m stations, respectively, of the Time-Of-Flight facility GELINA of the IRMM in Geel (B). The small amount of material allowed us to detect 13 resonances below 80 keV in the transmission measurements and 70 were seen in the capture measurements below 150 keV. The resonance parameters for the resonances seen in transmission agree within the uncertainties of the parameters determined by Horen et al. at ORELA. The capture yield was measured up to 600 keV and the capture areas for resonances up to 150 keV were compared with published data. This comparison reveals systematic differences, which are due to the detection geometry, the different neutron sensitivity in the detection systems, the applied weighting function, and normalisation.

  7. Taxonomy of factors which influence heavy metal build-up on urban road surfaces.

    PubMed

    Liu, An; Gunawardana, Chandima; Gunawardena, Janaka; Egodawatta, Prasanna; Ayoko, Godwin A; Goonetilleke, Ashantha

    2016-06-01

    Heavy metals build-up on urban road surfaces is a complex process and influenced by a diverse range of factors. Although numerous research studies have been conducted in the area of heavy metals build-up, limited research has been undertaken to rank these factors in terms of their influence on the build-up process. This results in limitations in the identification of the most critical factor/s for accurately estimating heavy metal loads and for designing effective stormwater treatment measures. The research study undertook an in-depth analysis of the factors which influence heavy metals build-up based on data generated from a number of different geographical locations around the world. Traffic volume was found to be the highest ranked factor in terms of influencing heavy metals build-up while land use was ranked the second. Proximity to arterial roads, antecedent dry days and road surface roughness has a relatively lower ranking. Furthermore, the study outcomes advances the conceptual understanding of heavy metals build-up based on the finding that with increasing traffic volume, total heavy metal build-up load increases while the variability decreases. The outcomes from this research study are expected to contribute to more accurate estimation of heavy metals build-up loads leading to more effective stormwater treatment design. PMID:26897571

  8. Adhesive strength of total knee endoprostheses to bone cement - analysis of metallic and ceramic femoral components under worst-case conditions.

    PubMed

    Bergschmidt, Philipp; Dammer, Rebecca; Zietz, Carmen; Finze, Susanne; Mittelmeier, Wolfram; Bader, Rainer

    2016-06-01

    Evaluation of the adhesive strength of femoral components to the bone cement is a relevant parameter for predicting implant safety. In the present experimental study, three types of cemented femoral components (metallic, ceramic and silica/silane-layered ceramic) of the bicondylar Multigen Plus knee system, implanted on composite femora were analysed. A pull-off test with the femoral components was performed after different load and several cementing conditions (four groups and n=3 components of each metallic, ceramic and silica/silane-layered ceramic in each group). Pull-off forces were comparable for the metallic and the silica/silane-layered ceramic femoral components (mean 4769 N and 4298 N) under standard test condition, whereas uncoated ceramic femoral components showed reduced pull-off forces (mean 2322 N). Loading under worst-case conditions led to decreased adhesive strength by loosening of the interface implant and bone cement using uncoated metallic and ceramic femoral components, respectively. Silica/silane-coated ceramic components were stably fixed even under worst-case conditions. Loading under high flexion angles can induce interfacial tensile stress, which could promote early implant loosening. In conclusion, a silica/silane-coating layer on the femoral component increased their adhesive strength to bone cement. Thicker cement mantles (>2 mm) reduce adhesive strength of the femoral component and can increase the risk of cement break-off. PMID:25781660

  9. Compacted sewage sludge as a barrier for tailings: the heavy metal speciation and total organic carbon content in the compacted sludge specimen.

    PubMed

    Zhang, Huyuan; Zhang, Qing; Yang, Bo; Wang, Jinfang

    2014-01-01

    Acid mine drainage (AMD) was the main environmental problem facing the mining industry. For AMD had high heavy metals content and low pH, the compacted sewage sludge might be a barrier for tailings whose oxidation and weathering produced AMD, with its own carbon source, microorganism reduction ability and impermeability. To study the heavy metals environmental risk, under the simulate AMD, the deionized water (DW), and the pH 2.1 sulfuric acid water (SA) seepage conditions, respectively, the changes of the chemical speciation of heavy metals Cd, Cu, Fe, Ni, Zn and total organic carbon (TOC) content in the compacted sewage sludge were assessed in the different periods. The results indicated according to the distribution of heavy metals, the potential mobility was for Cd: 6.08 under AMD, 7.48 under SA, ∞ under DW; for Cu: 0.08 under AMD, 0.17 under SA, 0.59 under DW; for Fe: 0.15 under AMD, 0.22 under SA, 0.22 under DW; for Ni: 2.60 under AMD, 1.69 under SA, 1.67 under DW; and for Zn: 0.15 under AMD, 0.23 under SA and 0.21 under DW at the second checking time. TOC content firstly decreased from 67.62±0% to 66.29±0.35%, then increased to 67.74±0.65% under the AMD seepage while TOC decreased to 63.30±0.53%, then to 61.33±0.37% under the DW seepage, decreased to 63.86±0.41%, then to 63.28±0.49% under SA seepage. That indicated under the AMD seepage, the suitable microorganisms communities in the compacted sewage sludge were activated. And the heavy metals environmental risk of compacted sewage sludge was lower with AMD condition than with other two. So the compacted sewage sludge as a barrier for tailings was feasible as the aspect of environmental risk assessment. PMID:24979755

  10. Compacted Sewage Sludge as a Barrier for Tailings: The Heavy Metal Speciation and Total Organic Carbon Content in the Compacted Sludge Specimen

    PubMed Central

    Zhang, Huyuan; Zhang, Qing; Yang, Bo; Wang, Jinfang

    2014-01-01

    Acid mine drainage (AMD) was the main environmental problem facing the mining industry. For AMD had high heavy metals content and low pH, the compacted sewage sludge might be a barrier for tailings whose oxidation and weathering produced AMD, with its own carbon source, microorganism reduction ability and impermeability. To study the heavy metals environmental risk, under the simulate AMD, the deionized water (DW), and the pH 2.1 sulfuric acid water (SA) seepage conditions, respectively, the changes of the chemical speciation of heavy metals Cd, Cu, Fe, Ni, Zn and total organic carbon (TOC) content in the compacted sewage sludge were assessed in the different periods. The results indicated according to the distribution of heavy metals, the potential mobility was for Cd: 6.08 under AMD, 7.48 under SA, ∞ under DW; for Cu: 0.08 under AMD, 0.17 under SA, 0.59 under DW; for Fe: 0.15 under AMD, 0.22 under SA, 0.22 under DW; for Ni: 2.60 under AMD, 1.69 under SA, 1.67 under DW; and for Zn: 0.15 under AMD, 0.23 under SA and 0.21 under DW at the second checking time. TOC content firstly decreased from 67.62±0% to 66.29±0.35%, then increased to 67.74±0.65% under the AMD seepage while TOC decreased to 63.30±0.53%, then to 61.33±0.37% under the DW seepage, decreased to 63.86±0.41%, then to 63.28±0.49% under SA seepage. That indicated under the AMD seepage, the suitable microorganisms communities in the compacted sewage sludge were activated. And the heavy metals environmental risk of compacted sewage sludge was lower with AMD condition than with other two. So the compacted sewage sludge as a barrier for tailings was feasible as the aspect of environmental risk assessment. PMID:24979755

  11. Metal impacts on microbial biomass in the anoxic sediments of a contaminated lake

    SciTech Connect

    Gough, Heidi L.; Dahl, Amy L.; Nolan, Melissa A.; Gaillard, Jean-Francois; Stahl, David A.

    2008-04-26

    Little is known about the long-term impacts of metal contamination on the microbiota of anoxic lake sediments. In this study, we examined microbial biomass and metals (arsenic, cadmium, chromium, copper, iron, lead, manganese, and zinc) in the sediments of Lake DePue, a backwater lake located near a former zinc smelter. Sediment core samples were examined using two independent measures for microbial biomass (total microscopic counts and total phospholipid-phosphate concentrations), and for various fractions of each metal (pore water extracts, sequential extractions, and total extracts of all studied metals and zinc speciation by X-ray absorption fine structure (XAFS). Zinc concentrations were up to 1000 times higher than reported for sediments in the adjacent Illinois River, and ranged from 21,400 mg/kg near the source to 1,680 mg/kg near the river. However, solid metal fractions were not well correlated with pore water concentrations, and were not good predictors of biomass concentrations. Instead, biomass, which varied among sites by as much as two-times, was inversely correlated with concentrations of pore water zinc and arsenic as established by multiple linear regression. Monitoring of other parameters known to naturally influence biomass in sediments (e.g., organic carbon concentrations, nitrogen concentrations, pH, sediment texture, and macrophytes) revealed no differences that could explain observed biomass trends. This study provides strong support for control of microbial abundance by pore water metal concentrations in contaminated freshwater sediments.

  12. Building Training on the Pillars: Applying Total Quality in the Classroom.

    ERIC Educational Resources Information Center

    Gallagher, Jo D.; And Others

    This paper focuses on the application of total quality management (TQM) in human resources development. It analyzes writings of five leading total quality authors from which four basic principles, or pillars, are derived as the basis for the application of total quality within the instructional setting. The pillars are: (1) customer satisfaction;…

  13. Influence of Toxicologically Relevant Metals on Human Epigenetic Regulation

    PubMed Central

    Lee, Dong Hoon; Won, Hye-Rim; Kim, Kyeong Hwan; Seong, Yun Jeong; Kwon, So Hee

    2015-01-01

    Environmental toxicants such as toxic metals can alter epigenetic regulatory features such as DNA methylation, histone modification, and non-coding RNA expression. Heavy metals influence gene expression by epigenetic mechanisms and by directly binding to various metal response elements in the target gene promoters. Given the role of epigenetic alterations in regulating genes, there is potential for the integration of toxic metal-induced epigenetic alterations as informative factors in the risk assessment process. Here, we focus on recent advances in understanding epigenetic changes, gene expression, and biological effects induced by toxic metals. PMID:25874027

  14. Solvated Electrons on Metal Oxide Surfaces

    SciTech Connect

    Zhao, Jin; Li, Bin; Onda, Ken; Feng, Min; Petek, Hrvoje

    2006-09-13

    An electron added to a solvent polarizes its surrounding medium to minimize the free energy. Such an electron with its polarization cloud, which we refer to as the solvated electron, is one of the most fundamental chemical reagents of significant experimental and theoretical interest. The structure and dynamics of solvated electrons in protic solvents have been explored ever since the discovery of intense blue coloration in solutions of alkali metals in ammonia.1-3 Because solvated electrons are the most fundamental chemical reagents as well as carriers of negative charge, substantial experimental and theoretical efforts have focused on elucidating their equilibrium structure and solvation dynamics in a variety of neat liquids.4,5 One of the most important but least explored environments for solvated electrons, namely, the two-dimensional liquid/solid and liquid/vacuum interfaces, is the subject of this review.

  15. Nano-donuts on metal surfaces

    NASA Astrophysics Data System (ADS)

    Rai, Abhishek; Nayak, Jayita; Roy Barman, Sudipta

    2015-03-01

    Nano-structures comprising of a pit surrounded by a circular ridge that resemble nano-donuts have been observed on flat terraces of both Au(1 1 1) and Al(1 0 0) surfaces after low energy (1.5-2 keV) rare gas (rg) ion implantation. From time lapse scanning tunneling microscopy, we demonstrate that these donuts originate from the rg bubbles that migrate out from the sub-surface region. The circular shape of the donuts is observed for both Ar and Ne bubbles. The donuts and the related nano-structures represent different stages of large time scale co-operative relaxation of Au atoms by long range elastic interaction after the rg bubbles leave the metal.

  16. Influence of Filler Metals in Welding Wires on the Phase and Chemical Composition of Weld Metal

    NASA Astrophysics Data System (ADS)

    Kozyrev, N. A.; Osetkovskiy, I. V.; Kozyreva, O. A.; Zernin, E. A.; Kartsev, D. S.

    2016-04-01

    The influence of filler metals used in welding wires on the phase and chemical composition of the metal, which is surfaced to mining equipment exposed to abrasive wear, has been investigated. Under a laboratory environment, samples of Mo-V-B and Cr-Mn-Mo-V wires were made. The performed experiments have revealed that fillers of the Cr-Mn-Mo-V system used in powder wire show better wear resistance of the weld metal than that of the Mn-Mo-V-B system; the absence of boron, which promotes grain refinement in the Mn-Mo-V-B system, significantly reduces wear resistance; the Mn-Mo-V-B weld metal has a finer structure than the Cr-Mn-Mo-V weld metal.

  17. Metallic glass coating on metals plate by adjusted explosive welding technique

    NASA Astrophysics Data System (ADS)

    Liu, W. D.; Liu, K. X.; Chen, Q. Y.; Wang, J. T.; Yan, H. H.; Li, X. J.

    2009-09-01

    Using an adjusted explosive welding technique, an aluminum plate has been coated by a Fe-based metallic glass foil in this work. Scanning electronic micrographs reveal a defect-free metallurgical bonding between the Fe-based metallic glass foil and the aluminum plate. Experimental evidence indicates that the Fe-based metallic glass foil almost retains its amorphous state and mechanical properties after the explosive welding process. Additionally, the detailed explosive welding process has been simulated by a self-developed hydro-code and the bonding mechanism has been investigated by numerical analysis. The successful welding between the Fe-based metallic glass foil and the aluminum plate provides a new way to obtain amorphous coating on general metal substrates.

  18. Friction moments of large metal-on-metal hip joint bearings and other modern designs.

    PubMed

    Bishop, N E; Waldow, F; Morlock, M M

    2008-10-01

    Modern hip joint replacements are designed to minimise wear problems. The most popular metal-on-polyethylene components are being updated by harder metal and ceramic combinations. However, this has also been shown to influence the friction moments, which could overload the interface between the implant and the body. In this study custom test apparatus was used to measure the joint moments in various modern bearings under simulated physiological joint conditions. The largest moments in serum were measured for large diameter metal-metal bearings (<8 Nm for standard bearings), followed by metal-polyethylene, and the lowest moments were for small diameter ceramic-ceramic and ceramic-metal combinations. Water as a lubricant was found to double the moments in comparison with serum. In metal-metal bearings moments were reduced by increasing loading frequency. Swing phase load and a rest period between load cycles had little effect. The moment magnitudes are within the turn-out capacity measured for press-fit cups and might become critical with higher joint loads. PMID:18291702

  19. Impacts of groundwater metal loads from bedrock fractures on water quality of a mountain stream.

    PubMed

    Caruso, Brian S; Dawson, Helen E

    2009-06-01

    Acid mine drainage and metal loads from hardrock mines to surface waters is a significant problem in the western USA and many parts of the world. Mines often occur in mountain environments with fractured bedrock aquifers that serve as pathways for metals transport to streams. This study evaluates impacts from current and potential future groundwater metal (Cd, Cu, and Zn) loads from fractures underlying the Gilt Edge Mine, South Dakota, on concentrations in Strawberry Creek using existing flow and water quality data and simple mixing/dilution mass balance models. Results showed that metal loads from bedrock fractures to the creek currently contribute <1% of total loads. Even if background water quality is achieved upstream in Strawberry Creek, fracture metal loads would be <5%. Fracture loads could increase substantially and cause stream water quality standards exceedances once groundwater with elevated metals concentrations in the aquifer matrix migrates to the fractures and discharges to the stream. Potential future metal loads from an upstream fracture would contribute a small proportion of the total load relative to current loads in the stream. Cd has the highest stream concentrations relative to standards. Even if all stream water was treated to remove 90% of the Cd, the standard would still not be achieved. At a fracture farther downstream, the Cd standard can only be met if the upstream water is treated achieving a 90% reduction in Cd concentrations and the median stream flow is maintained. PMID:18604589

  20. Interactive effects of pollination and heavy metals on resource allocation in Potentilla anserina L.

    SciTech Connect

    Saikkonen, K. |; Koivunen, S.; Vuorisalo, T.; Mutikainen, P. |

    1998-07-01

    The authors studied resource allocation between sexual reproduction and clonal propagation in a perennial stoloniferous clonal plant, Potentilla anserina, an obligate outcrosser. They manipulated reproductive effort of Potentilla anserina either by hand-pollinating all flowers or by preventing pollination. To test the effect of resource-limiting conditions on resource allocation and reproductive output, the authors used a control and two levels of heavy metals (copper and nickel) to limit plant growth. The experiment was conducted as a 2 {times} 3 factorial design to reveal possible interactions between reproductive manipulation and resource limitation. Heavy metals decreased the total biomass of the plants and number of flowers and ramets produced. Only 50% of the plants grown with the higher level of heavy metals produced flowers. Pollination treatment interacted significantly with the heavy-metal treatment. In the metal control and lower heavy-metal treatment, there were no significant differences in total vegetative biomass between the two pollination treatments. Costs of reproduction in terms of subsequent flowering in the later season appeared to be clear, because the number of flowers per whole plant was lower if the plants were hand-pollinated and because the proportion of flowering ramets decreased due to hand-pollination. However, flowering may also be partly hormonally controlled. In contrast, hand-pollinated plants exposed to high concentrations of heavy metals tended to have greater biomass of vegetative plant structures and higher number of flowers compared to nonpollinated plants.

  1. Metallic nanoshells on porphyrin-stabilized emulsions

    DOEpatents

    Wang, Haorong; Song, Yujiang; Shelnutt, John A; Medforth, Craig J

    2013-10-29

    Metal nanostructures formed by photocatalytic interfacial synthesis using a porphyrin-stabilized emulsion template and the method for making the nanostructures. Catalyst-seeded emulsion droplets are employed as templates for hollow-nanoshell growth. The hollow metal nanospheres may be formed with or without inclusions of other materials.

  2. Forming Weld Lands On Metal Plates

    NASA Technical Reports Server (NTRS)

    Weddendorf, Bruce

    1994-01-01

    Forming shoe pounds edge of newly inserted plate workpiece. After many passes of shoe and advances of plate, thick land builds up at edge. Workpiece heated to enable metal to flow without strain hardening. Proposed upset-forming process replaces relatively expensive, time-consuming, and wasteful process in which integral weld lands created by machining metal away from plates everywhere except at lands.

  3. The nutrient, total petroleum hydrocarbon and heavy metal contents in the seawater of Bohai Bay, China: Temporal-spatial variations, sources, pollution statuses, and ecological risks.

    PubMed

    Peng, Shitao

    2015-06-15

    Seawater samples collected between 2007 and 2012 were determined the concentrations of nutrient (DIN and DIP), total petroleum hydrocarbon (TPH), and six different heavy metals (As, Cu, Zn, Pb, Cd and Hg). The DIN, DIP, TPH, Pb, and Cd concentrations decreased from 2007 to 2009 or 2010 and increased after 2010. However, the Hg and Cu concentrations increased from 2007 to 2012. In contrast, the As and Zn gradually decreased during the study period. All of the pollutant concentrations gradually decreased from the shoreline to the offshore sites. PCA result showed that urban and port areas, agriculture, and atmospheric deposition were the main sources of pollutants in the bay. Although most of the pollutants were present at concentrations bellow the highest seawater quality standards in China, eutrophication was a risk in Bohai Bay. In addition, DIN was the main pollutant and was responsible for the eutrophication risk in Bohai Bay. PMID:25840871

  4. Ultrasound-assisted single extraction tests for rapid assessment of metal extractability from soils by total reflection X-ray fluorescence.

    PubMed

    De La Calle, I; Cabaleiro, N; Lavilla, I; Bendicho, C

    2013-09-15

    In this work, ultrasound-assisted extraction (UAE) was employed for acceleration of metal extraction from soil samples. After extraction, multielemental analysis (Cr, Mn, Fe, Ni, Cu, Zn and Pb) of EDTA and acetic acid extracts was performed by total reflection X-ray fluorescence spectrometry (TXRF). High-intensity ultrasonic processors, i.e. the ultrasonic probe (50W) and the cup-horn sonoreactor (200W) were applied. Both ultrasonic procedures were compared with a miniaturized version of the single extraction scheme proposed by the Standards, Measurements and Testing program (SM&T). The extraction time with EDTA was reduced from 1h (conventional procedure) to 2 min (ultrasonic probe) or to 10 min (cup-horn sonoreactor). The time required for acetic acid extraction was also reduced from 16 h (conventional procedure) to 6 min (ultrasonic probe) or to 30 min (cup-horn sonoreactor). In addition, the amount of sample and extractants was drastically reduced as a result of the miniaturization implemented in the developed approaches. The combination of UAE and TXRF allows assessing the potential metal mobility and bioavailability in a simple way. PMID:23770487

  5. Accumulations of total metal in dominant shrimp species (Palaemon adspersus, Palaemon serratus, Parapenaeus longirostris) and bottom surface sediments obtained from the Northern Inner Shelf of the Sea of Marmara.

    PubMed

    Kurun, A; Balkis, H; Balkis, N

    2007-12-01

    The aim of this study is to determine the total metal (aluminum, copper, manganese, nickel, lead, zinc, cadmium, iron, mercury) contents of dominant shrimp species and sediments present at 1-50 m depths of the Northern Inner Shelf of the Sea of Marmara. Shrimp and sediment samples were collected from four regions (Büyükçekmece, Silivri, Tekirdağ, Sarköy) and from different depths (1, 5, 10, 20, 30, 50 m) at each region in September and November of 2003. Three shrimp species [Palaemon adspersus (Rathke, 1937), Palaemon serratus (Pennant, 1777), Parapenaeus longirostris (H. Lucas, 1846)] were identified to be dominant as a result of the examination on the obtained samples. Heavy metal contents of these three species were determined and the results were compared with the acceptable treshold values of the Seafood Standards and also with available literatures. The Cu contents were found to be higher than the treshold limits in all samples except P. longirostris from Silivri, also the Cd contents in all samples except P. adspersus from Büyükçekmece, the Zn contents only in P. adspersus and P. longirostris from Tekirdağ, and the Pb contents in all species from all regions. These high values are the indicator of industrial pollution. There is not any data in the Seafood Standards about Mn, Ni, Fe and Al contents in shrimp species. The values of these metal contents were given in the present study. The examination of total metal distributions in bottom surface sediment samples in the Northern Inner Shelf of the Sea of Marmara showed that the determined values were higher than the shale average at some depths of examined stations. PMID:17406997

  6. A FUNCTIONAL AND ROENTGENOGRAPHIC PRELIMINARY COMPARATIVE STUDY USING METAL-BACKED AND ALL-POLYETHYLENE TIBIAL COMPONENTS IN TOTAL KNEE ARTHROPLASTY

    PubMed Central

    de Andrade, Marco Antônio Percope; dos Santos, Juliano Rodrigues; Gonzaga, Luiz Gustavo Alves; Silva, Guilherme Moreira Abreu e

    2015-01-01

    Objective: To describe and clinically and radiographically compare patients who underwent total knee arthroplasty (TKA) with all-polyethylene (ALP) and metal-backed (MTB) tibial implants. Methods: Patients who underwent TKA between January 1988 and December 2004 were grouped according to the type of implant received: all-polyethylene or metal-backed. Sixty patients came for evaluations, totaling 82 operated knees. Among these, 22 patients had undergone TKA only with ALP (12 unilateral and 10 bilateral cases), 33 patients only with MTB (26 unilateral and 7 bilateral cases) and five patients underwent TKA with ALP in one knee and MTB in the other. The knees were divided thus: group 1, 37 knees with ALP; and group 2, 45 knees with MTB. Results: There were no differences in clinical or functional evaluations between the groups. The mean radiolucency in the femur was 0.838 mm for the patients in group 1 and 0.356 mm for the patients in group 2 (p = 0.049). For the tibia, in the AP view, there was a mean value of 2.703 mm for group 1 and 0.733 mm for group 2 (p = 0.000). In the lateral view, the mean values for osteolysis was 0.405 mm for group 1 and 0.200 mm for group 2 (p = 0.074). Conclusions: There were no differences between the groups in the functional and clinical evaluations. However, greater radiolucency was observed in the arthroplasties with ALP, both in the femur in the lateral view and in the tibia in the AP view. Level of evidence IV – case series study. PMID:27022556

  7. A new CT metal artifacts reduction algorithm based on fractional-order sinogram inpainting.

    PubMed

    Zhang, Yi; Pu, Yi-Fei; Hu, Jin-Rong; Liu, Yan; Zhou, Ji-Liu

    2011-01-01

    In this paper, we propose a new metal artifacts reduction algorithm based on fractional-order total-variation sinogram inpainting model for X-ray computed tomography (CT). The numerical algorithm for our fractional-order framework is also analyzed. Simulations show that, both quantitatively and qualitatively, our method is superior to conditional interpolation methods and the classic integral-order total variation model. PMID:21876286

  8. Comparative study of metal adsorption on the metal and the oxide surfaces

    NASA Astrophysics Data System (ADS)

    Magkoev, T. T.; Vladimirov, G. G.; Remar, D.; Moutinho, A. M. C.

    2002-05-01

    Adsorption of Ti, Cr, Fe, Ni and Cu atoms at coverage not exceeding two monolayers on the surface of ultrathin (10-15 Å) alumina and magnesia films (γ-Al 2O 3(111) or α-Al 2O 3(1000) and MgO(111) grown on Mo(110) were studied in ultrahigh vacuum by means of electron spectroscopy techniques (Auger electron spectroscopy (AES), electron energy loss spectroscopy (EELS), high resolution electron energy loss spectroscopy (HREELS), low energy electron diffraction (LEED), work function measurements and reflection absorption infrared spectroscopy (RAIRS)). At very low metal coverage and low substrate temperature (85 K) when the film can be viewed as consisting of separate adatoms and/or very small clusters the electronic properties of adatoms on the oxide films, on one hand, and on Mo(110) surface, on the other hand, are quite different. With increasing metal coverage, the properties on both the oxide and the metallic substrates change becoming similar at the coverage close to monolayer. On the Mo(110) surface the electronic properties change gradually with the metal coverage, whereas on the oxide there is a critical coverage of about 0.15 ML separating ionic and metallic adsorption of the metal species. It is shown that the lateral interaction of adatoms on the oxide surface plays a dominant role in the formation of the band-like structure of the adsorbed 2D film.

  9. Influence of head size on the development of metallic wear and on the characteristics of carbon layers in metal-on-metal hip joints

    PubMed Central

    Sprecher, Christoph M; Wimmer, Markus A; Milz, Stefan; Taeger, Georg

    2009-01-01

    Background and purpose Particles originating from the articulating surfaces of hip endoprostheses often induce an inflammatory response, which can be related to implant failure. We therefore analyzed the metal content in capsular tissue from 44 McKee-Farrar metal-on-metal hip prostheses (with 3 different head sizes) and we also analyzed the morphological structure of layers located on articulating surfaces. Methods Atomic absorption spectrometry (AAS) was used to analyze the metal content in capsular tissue. Visually detectable carbon layers located on the articulating surfaces were evaluated using scanning electron microscopy (SEM), energy-dispersive Xray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). Results Metallic debris was detected in all capsular tissue samples but no statistically significant differences in metal content were found in relation to implant head size. The morphological characteristics of the different layer zones allowed an exact analysis of contact and non-contact areas. Furthermore, surface layers appear to have a protective function because they can prevent sharp-edged particles from damaging the prostheses surface. Interpretation The implant head size does not appear to influence the amount of metallic debris. The layers obviously act like a lubricating agent because the protection function does not occur in regions without layers where the metal surface often shows numerous scratches. As layers are not generated immediately after the implantation of hip prostheses, these findings may at least partially explain the high amount of wear early after implantation. PMID:19421914

  10. A Study on the Optimization for Metal Injection Molding Process

    NASA Astrophysics Data System (ADS)

    Jung, M. K.; Jang, K. C.; Lee, D. G.; Kim, M. H.

    2011-01-01

    The objective of this paper is study the optimization for metal injection molding process by using the design of experiments (DOE) and numerical analysis. In order to determine optimal process parameters, experiment and computerized analysis have been performed for various process conditions. Proper coded and uncoded regression equations and optimization for responses (flow front temperature, part weight, filling time, cycle time, and volumetric shrinkage) achieved from studying and verifying interrelation of the factors. About 70% of whole binder extracted within about 10 minutes and temperature of solvent is higher, the debinding rate is fast. 50° C was the most suitable condition for solvent extraction because of crack occurrence on green body at 55° C. It took about 14.5 hours to perform secondary thermal debinding, which was only about 35% of the entire time taken compared with single thermal debinding process, even if it considers solvent extraction time required. Therefore, the applied method greatly reduces the debinding time. The excellent process capability showed that the PPM total and Z.Bench were 9,946.8 and 2.33 showing good quality rate of around 99.01% and sigma level of 3.83. As a result, the process and optimization have been improved, and the proposed approach could be successfully reflected on the metal injection molding.

  11. Thin films of metal oxides on metal single crystals: Structure and growth by scanning tunneling microscopy

    SciTech Connect

    Galloway, H.C.

    1995-12-01

    Detailed studies of the growth and structure of thin films of metal oxides grown on metal single crystal surfaces using Scanning Tunneling Microscopy (STM) are presented. The oxide overlayer systems studied are iron oxide and titanium oxide on the Pt(III) surface. The complexity of the metal oxides and large lattice mismatches often lead to surface structures with large unit cells. These are particularly suited to a local real space technique such as scanning tunneling microscopy. In particular, the symmetry that is directly observed with the STM elucidates the relationship of the oxide overlayers to the substrate as well as distinguishing, the structures of different oxides.

  12. Clinical usefulness of blood metal measurements to assess the failure of metal-on-metal hip implants

    PubMed Central

    Sampson, Barry; Hart, Alister

    2012-01-01

    In April 2010, a Medicines and Healthcare Products Regulatory Agency safety alert concerning all metal-on-metal (MOM) hip replacements recommended measuring chromium and cobalt concentrations when managing patients with painful prostheses. The need for this review is illustrated by the recent surge in requests for these blood tests from orthopaedic surgeons following this alert. The aim is to provide guidance to laboratories in assessing these requests and advising clinicians on interpretation. First, we summarize the basic terminology regarding the types of hip replacements, with emphasis on the MOM type. Second, we describe the clinical concerns over implant-derived wear debris in the local tissues and distant sites. Analytical aspects of the measurement of the relevant metal ions and what factors affect the levels measured are discussed. The application of inductively coupled plasma mass spectrometry techniques to the measurement of these metals is considered in detail. The biological effects of metal wear products are summarized with local toxicity and systemic biological effects considered, including carcinogenicity, genotoxicity and systemic toxicity. Clinical cases are used to illustrate pertinent points. PMID:22155921

  13. Effects of spatial and temporal variation in metal availability on earthworms in floodplain soils of the river Dommel, The Netherlands.

    PubMed

    Bleeker, Eric A J; van Gestel, Cornelis A M

    2007-08-01

    Regarding impact on ecological soil functioning, metal pollution is often considered a constant factor for certain sampling sites. However, especially bioavailable concentrations may differ in space and time. This aspect was investigated on four sites along a metal-polluted river, differing in soil characteristics and metal concentrations. Every four weeks earthworm densities, soil characteristics, and metal concentrations in soil and earthworms were determined. Earthworm biomass and density fluctuated in time and increased with increasing metal contamination, indicating the presence of compensating factors. Multivariate analysis suggested organic matter and moisture content to be the main factors explaining earthworm biomass. Metal concentrations in the earthworms increased with increasing total or 0.01M CaCl(2) extractable soil concentrations, but no time-related trends were seen. Cadmium concentrations in the earthworms exceeded background values, suggesting a potential risk. The neutral red retention biomarker assay, however, did not show any signs of metal stress in the earthworms. PMID:17376569

  14. 75 FR 76037 - General Motors Corporation Grand Rapids Metal Center Metal Fabricating Division Including On-Site...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-07

    ... published in the Federal Register on April 23, 2010 (75 FR 21356). At the request of the State agency, the... Employment and Training Administration General Motors Corporation Grand Rapids Metal Center Metal Fabricating..., applicable to workers of General Motors Corporation, Grand Rapids Metal Center, Metal Fabricating...

  15. Large-area experiment on uptake of metals by twelve plants growing in soils contaminated with multiple metals.

    PubMed

    Lai, Hung-Yu; Juang, Kai-Wei; Chen, Zueng-Sang

    2010-01-01

    A site in central Taiwan with an area of 1.3 ha and contaminated with Cr, Cu, Ni, and Zn was selected to examine the feasibility of phytoextraction. Based on the results of a preexperiment at this site, a total of approximately 20,000 plants of 12 species were selected from plants of 33 tested species to be used in a large-area phytoextraction experiment at this site. A comparison with the initial metal concentration of 12 plant species before planting demonstrated that most species accumulated significant amounts of Cr, Cu, Ni, and Zn in their shoots after growing in this contaminated site for 31 d. Among the 12 plant species, the following accumulated higher concentrations of metals in their shoots; Garden canna and Garden verbena (45-60 mg Cr kg(-1)), Chinese ixora and Kalanchoe (30 mg Cu kg(-1)), Rainbow pink and Sunflower (30 mg Ni kg(-1)), French marigold and Sunflower (300-470 mg Zn kg(-1)). The roots of the plants of most of the 12 plant species can accumulate higher concentrations of metals than the shoots and extending the growth period promotes accumulation in the shoots. Large-area experiments demonstrated that phytoextraction is a feasible method to enable metal-contaminated soil in central Taiwan to be reused. PMID:21166348

  16. Fate and effects of heavy metals on the Arkansas river

    SciTech Connect

    Clements, W.H.

    1991-12-15

    The project examined fate and effects of heavy metals on biological communities in the upper Arkansas River Basin. The principal objectives of the research were: (1) to measure the impact of heavy metals (Cd, Cu, and Zn) on benthic invertebrate communities in the Arkansas River; (2) to delineate zones of high impact, moderate impact, and recovery based on the distribution and abundance of these organisms; (3) to examine seasonal variation in effects of metals on benthic communities; (4) to examine the potential transfer of heavy metals from benthic invertebrates to brown trout, Salmo trutta.

  17. Perivascular Lymphocytic Infiltration Is Not Limited to Metal-on-Metal Bearings

    PubMed Central

    Ng, Vincent Y.; Berend, Keith R.; Skeels, Michael D.; Adams, Joanne B.

    2010-01-01

    Background Perivascular lymphocytic infiltration (PVLI) suggests an adaptive immune response. Metal hypersensitivity after THA is presumed associated with idiopathic pain and aseptic loosening, but its incidence and relationship to metallic wear leading to revision are unclear as are its presence and relevance in non-metal-on-metal arthroplasty. Questions/purposes We compared (1) incidence and severity of PVLI in failed hip metal-on-metal (MoM) to non-MoM implants and TKA; (2) PVLI in MoM and non-MoM hip arthroplasty based on reason for revision; and (3) PVLI grade to diffuse lymphocytic infiltration (DLI) and tissue reaction to metal particles. Patients and Methods We retrospectively examined incidence and severity of PVLI, DLI, and tissue reaction in periprosthetic tissue from 215 THA and 242 TKA revisions including 32 MoM hips. Results Perivascular lymphocytic infiltration was present in more TKAs (40%) than overall hip arthroplasties (24%) without difference in severity. Compared to non-MoM hips, MoM bearings were more commonly associated with PVLI (59% versus 18%) and demonstrated increased severity (41% versus 3% greater than mild). Histologically, PVLI correlated (r = 0.51) with DLI, but not tissue reaction. In THA, PVLI was most commonly associated with idiopathic pain (70%) and aseptic loosening (54%) in MoM, and infection in all hip revisions (53%). Conclusions Perivascular lymphocytic infiltration is more extensive in revisions of MoM and in aseptic loosening, idiopathic pain, or infection but is also present in TKA, non-MoM, and different reasons for revision. It correlates with other signs of metal hypersensitivity, but not with histologic measures of metal particulate load. Level of Evidence Level III, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence. PMID:20878289

  18. Plasma-Spray Metal Coating On Foam

    NASA Technical Reports Server (NTRS)

    Cranston, J.

    1994-01-01

    Molds, forms, and other substrates made of foams coated with metals by plasma spraying. Foam might be ceramic, carbon, metallic, organic, or inorganic. After coat applied by plasma spraying, foam left intact or removed by acid leaching, conventional machining, water-jet cutting, or another suitable technique. Cores or vessels made of various foam materials plasma-coated with metals according to method useful as thermally insulating containers for foods, liquids, or gases, or as mandrels for making composite-material (matrix/fiber) parts, or making thermally insulating firewalls in automobiles.

  19. Heavy metal fractionation and pedogenesis in subalpine and alpine soils on ophiolitic materials, western Alps

    NASA Astrophysics Data System (ADS)

    D'Amico, M.; Previtali, F.

    2009-04-01

    ), all the fractions of Ni, Co and Mn are strictly correlated with each other: in A and Bs horizons, the greatest amount is associated with organic matter and with crystalline Fe-oxides. The content in easily mobilizable forms associated with Mn and amorphous Fe oxides is only slightly lower. The greatest amount is in the residual fraction, as pedogenic forms are easily removed from the soil profiles by leaching; this is particularly evident in E horizons. Cr is less released by weathering, and the greatest fraction is associated with organic matter and amorphous Fe-oxides. No Cr could be detected associated with Mn oxides. The high mobility of metals in these soils increases their bioavailability. Above the treeline, the situation changes dramatically. Leaching is important only on stable, flat surfaces. Total and pedogenic fractions of Ni, Cr, Co and Fe increase from the bottom to the top of the soil profile, while all forms of Mn are strongly depleted in the upper horizons because of chemical reduction due to waterlogging at snowmelt. In fact, Mn is particularly sensitive to reduction processes. The most important factors involved in metal geochemistry are erosion and cryoturbation, which bring "fresh", metal-rich materials on the top of the profiles; weathering later releases the metals associated with pedogenic materials. The weak leaching due to limited acidification increases the concentration of potentially bioavailable metals (Fe, Co, Cr, and Ni) in the biologically active soil horizons. All metals are mobilized by waterlogging at snowmelt: extremely high contents of "labile" pedogenic forms of metals also in deep horizons of soils developed on metal-poor materials. However, the concentration due to the processes described above is stronger than leaching for Ni, Co, Fe and Cr.

  20. Study on metal ejection under laser shock loading

    NASA Astrophysics Data System (ADS)

    Jianting, Xin; Yuqiu, Gu

    2013-06-01

    Dynamic response of metal to shock loading plays an important role in the fields of civil engineering, aeronautics etc. The loading method of intense laser driven shock wave has many advantages to study the ejection process. The present work is devoted to laser-shock experiments in metal ejection, and get access to fragments recovery and post-test evaluation of the fragment-size distribution. The experiments were carried out on the SGIII laser facility, the samples are tin foil of 106 μm and 260 μm. Two high power pulsed laser beams of 0.532 μm wavelength are focused onto the target, the laser beams were homogenized by cpp, and the irradiated spot is quasi circular with 2mm diameter. The dynamic fragmentation were recovered by CH foam with 200 mg/cm3 density. One dimensional simulations were performed with HYADES code, and the pressures near the free surface of the targets driven by laser in experiments are 13 Gpa, 27 Gpa, 42 Gpa and 50 Gpa respectively. We observed the fragments in the CH foam tube by X-ray radiographs and CT image reconstruction. The total number and characteristic size of fragments have been detected.

  1. Influence of Deuterium Treatments on the Polysilicon-Based Metal-Semiconductor-Metal Photodetector.

    PubMed

    Lee, Jae-Sung

    2016-06-01

    The electrical behavior of metal-semiconductor-metal (MSM) Schottky barrier photodetector structure, depending on deuterium treatment, is analyzed by means of the dark current and the photocurrent measurements. Al/Ti bilayer was used as Schottky metal. The deuterium incorporation into the absorption layer, undoped polysilicon, was achieved with annealing process and with ion implantation process, respectively. In the photocurrent-to-dark current ratio measurement, deuterium-ion-implanted photodetector shows over hundred higher than the control device. It means that the heightening of the Schottky barrier and the passivation of grain boundary trap were achieved effectively through the deuterium ion implantation process. PMID:27427689

  2. Resistive switching based on filaments in metal/PMMA/metal thin film devices

    NASA Astrophysics Data System (ADS)

    Wolf, Christoph; Nau, Sebastian; Sax, Stefan; Busby, Yan; Pireaux, Jean-Jacques; List-Kratochvil, Emil J. W.

    2015-12-01

    The working mechanism of unipolar organic resistive switching thin-film devices is investigated. On the basis of a metal/poly(methyl methacrylate)/metal model system, direct spectroscopic evidence for filament formation is obtained by three-dimensional (3D) imaging with time-of-flight secondary ion mass spectrometry. By means of alternative fabrication methods the claimed influence of metal implantation in the organic layer during fabrication is ruled out. Further, the stability of the resistive switches under oxygen and humidity is investigated leading to a deeper understanding of the processes governing the formation and rupture of filaments.

  3. Roles of lattice cooling on local heating in metal-molecule-metal junctions

    NASA Astrophysics Data System (ADS)

    Tsutsui, Makusu; Taniguchi, Masateru; Yokota, Kazumichi; Kawai, Tomoji

    2010-03-01

    We report a quantitative assessment of the efficacy of lattice cooling on mitigating local heating in a current-carrying single molecule wire connected to gold nanoelectrodes by comparative analyses of high-field effective temperatures at different ambient temperatures. We find substantial local heating in benzenedithiol single molecule junctions raising the local temperatures by ˜320 K from the ambient to ˜400 K at 0.85 V. The intense self-heating are attributable to decreased thermal conductance at low temperatures that leads to deteriorated heat transfer at metal-molecule contacts, thereby manifesting a critical role of lattice cooling for alleviating metal-molecule-metal junction overheating.

  4. Diagnosis of adverse local tissue reactions following metal-on-metal hip arthroplasty.

    PubMed

    Chalmers, Brian P; Perry, Kevin I; Taunton, Michael J; Mabry, Tad M; Abdel, Matthew P

    2016-03-01

    Metal-on-metal (MOM) bearing surfaces in hip arthroplasty have distinct advantages that led to the increase in popularity in North America in the early 2000s. However, with their increased use, concerns such as local cytotoxicity and hypersensitivity reactions leading to soft tissue damage and cystic mass formation (known collectively as adverse local tissue reactions (ALTR)) became apparent. The clinical presentation of ALTR is highly variable. The diagnosis of ALTR in MOM articulations in hip arthroplasty can be challenging and a combination of clinical presentation, physical examination, implant track record, component positioning, serum metal ion levels, cross-sectional imaging, histopathologic analysis, and consideration of alternative diagnoses are essential. PMID:26816329

  5. Determination and chemometric evaluation of total aflatoxin, aflatoxin B1, ochratoxin A and heavy metals content in corn flours from Turkey.

    PubMed

    Algül, Işıl; Kara, Derya

    2014-08-15

    Concentrations of the total aflatoxin, aflatoxin B1, aflatoxin B2, aflatoxin G1, aflatoxin G2, ochratoxin A, lead, cadmium, mercury, arsenic, copper, zinc and chromium in corn flour samples were determined. Eighteen corn flour samples that were obtained from different cities and villages in Turkey and 3 corn flour samples obtained from the UK. Determination of the different toxins was carried out using HPLC instrumentation after pre-separation using immunoaffinity columns that work through a mechanism of solid-phase extraction. An ICP-MS instrument was used for the heavy metal determinations. The results obtained from HPLC and ICP-MS analyses of the corn flour samples showed that these samples contain detectable levels of most of the analytes but the mercury was at undetectable levels. A very strong statistical relationship was observed between Cr and total Aflatoxin and Aflatoxin B1; whereas Ochratoxin A was related to Cu and Zn concentrations using correlation analyses and principal component analyses. PMID:24679753

  6. Effects of simulated lightning on composite and metallic joints

    NASA Technical Reports Server (NTRS)

    Howell, W. E.; Plumer, J. A.

    1982-01-01

    The effects of simulated lightning strikes and currents on aircraft bonded joints and access/inspection panels were investigated. Both metallic and composite specimens were tested. Tests on metal fuel feed through elbows in graphite/epoxy structures were evaluated. Sparking threshold and residual strength of single lap bonded joints and sparking threshold of access/inspection panels and metal fuel feed through elbows are reported.

  7. Plant Rhizosphere Effects on Metal Mobilization and Transport

    SciTech Connect

    Fan, Teresa W.-M; Crowley, David; Higashi, Richard M.

    1999-06-01

    A mechanistic understanding of mobilization or immobilization of nutrient and pollutant metal ions by plants is largely lacking. It begins with a lack of knowledge on the chemical nature of rhizosphere components that are reactive with metal ions. This fundamental knowledge is critical to the design and implementation of phytoremediation for metal-contaminated DOE sites. Therefore, the objectives of this project include (1) To obtain a comprehensive composition of major organic components in plant root exudates as a function of different metal ions and plant species; (2) To examine plant metabolic response(s) to these metal ion treatments, with emphasis on production of metal reactive compounds; (3) To investigate the effect(s) of soil microbial (e.g. mycorrhizae) association on (1) and (2).

  8. Wear mechanisms in metal-on-metal bearings: the importance of tribochemical reaction layers.

    PubMed

    Wimmer, Markus A; Fischer, Alfons; Büscher, Robin; Pourzal, Robin; Sprecher, Christoph; Hauert, Roland; Jacobs, Joshua J

    2010-04-01

    Metal-on-metal (MoM) bearings are at the forefront in hip resurfacing arthroplasty. Because of their good wear characteristics and design flexibility, MoM bearings are gaining wider acceptance with market share reaching nearly 10% worldwide. However, concerns remain regarding potential detrimental effects of metal particulates and ion release. Growing evidence is emerging that the local cell response is related to the amount of debris generated by these bearing couples. Thus, an urgent clinical need exists to delineate the mechanisms of debris generation to further reduce wear and its adverse effects. In this study, we investigated the microstructural and chemical composition of the tribochemical reaction layers forming at the contacting surfaces of metallic bearings during sliding motion. Using X-ray photoelectron spectroscopy and transmission electron microscopy with coupled energy dispersive X-ray and electron energy loss spectroscopy, we found that the tribolayers are nanocrystalline in structure, and that they incorporate organic material stemming from the synovial fluid. This process, which has been termed "mechanical mixing," changes the bearing surface of the uppermost 50 to 200 nm from pure metallic to an organic composite material. It hinders direct metal contact (thus preventing adhesion) and limits wear. This novel finding of a mechanically mixed zone of nanocrystalline metal and organic constituents provides the basis for understanding particle release and may help in identifying new strategies to reduce MoM wear. PMID:19877285

  9. Assessing the ecotoxicological effects of long-term contaminated mine soils on plants and earthworms: relevance of soil (total and available) and body concentrations.

    PubMed

    García-Gómez, Concepción; Esteban, Elvira; Sánchez-Pardo, Beatriz; Fernández, María Dolores

    2014-09-01

    The interactions and relevance of the soil (total and available) concentrations, accumulation, and acute toxicity of several essential and non-essential trace elements were investigated to determine their importance in environmental soil assessment. Three plant species (T. aestivum, R. sativum, and V. sativa) and E. fetida were simultaneously exposed for 21 days to long-term contaminated soils collected from the surroundings of an abandoned pyrite mine. The soils presented different levels of As and metals, mainly Zn and Cu, and were tested at different soil concentrations [12.5, 25, 50, and 100% of contaminated soil/soil (w/w)] to increase the range of total and available soil concentrations necessary for the study. The total concentrations in the soils (of both As and metals) were better predictors of earthworm uptake than were the available concentrations. In plants, the accumulation of metals was related to the available concentrations of Zn and Cu, which could indicate that plants and earthworms accumulate elements from different pools of soil contaminants. Moreover, Zn and Cu, which are essential elements, showed controlled uptake at low concentrations. The external metal concentrations predicted earthworm mortality, whereas in plants, the effects on growth were correlated to the As and metal contents in the plants. In general, the bioaccumulation factors were lower at higher exposure levels, which implies the existence of auto-regulation in the uptake of both essential and non-essential elements by plants and earthworms. PMID:24875255

  10. ON THE METALLICITIES OF KEPLER STARS

    SciTech Connect

    Dong, Subo; Zheng, Zheng; Zhu, Zhaohuan; De Cat, P.; Fu, J. N.; Yang, X. H.; Zhang, Haotong; Jin, Ge; Zhang, Yong

    2014-07-01

    We use 12,000 stars from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) spectroscopic survey data to show that the metallicities of Kepler field stars as given in the Kepler Input Catalog (KIC) systematically underestimate both the true metallicity and the dynamic range of the Kepler sample. Specifically, to the first order approximation, we find [Fe/H]{sub KIC} = –0.20 + 0.43[Fe/H]{sub LAMOST}, with a scatter of ∼0.25 dex, due almost entirely to errors in KIC. This relation is most secure for –0.3 < [Fe/H]{sub LAMOST} < +0.4 where we have >200 comparison stars per 0.1 dex bin and good consistency is shown between metallicities determined by LAMOST and high-resolution spectra. It remains approximately valid in a slightly broader range. When the relation is inverted, the error in true metallicity as derived from KIC is (0.25 dex)/0.43-0.6 dex. We thereby quantitatively confirm the cautionary note by Brown et al. that KIC estimates of [Fe/H] should not be used by {sup a}nyone with a particular interest in stellar metallicities{sup .} Fortunately, many more LAMOST spectroscopic metallicities will be available in the near future.

  11. Effects of lime on bioavailability and leachability of heavy metals during agitated pile composting of water hyacinth.

    PubMed

    Singh, Jiwan; Kalamdhad, Ajay S

    2013-06-01

    In the present study composting of water hyacinth was done with cattle manure and saw dust (6:3:1) ratio and effects of addition of lime (1%, 2% and 3%) on heavy metal bioavailability and leachability was evaluated during 30 days of composting period. The changes in temperature, pH, electrical conductivity (EC), organic matter and extractable heavy metal contents were measured. Results showed that the total concentration of heavy metals was increased during the composting process. Due to addition of lime initial pH of the compost was raised effectively, caused a decrease in water soluble, diethylene triamine pentracetic acid (DTPA) and toxicity characteristics leaching procedure (TCLP) extractable metal contents in the final compost. Water soluble metals (Ni, Pb and Cd) and DTPA extractable metals (Pb and Cd) were not detected during water soluble fraction. Addition of lime significantly reduced the bioavailability and leachability of heavy metals during water hyacinth composting process. PMID:23612174

  12. Patterning Superatom Dopants on Transition Metal Dichalcogenides.

    PubMed

    Yu, Jaeeun; Lee, Chul-Ho; Bouilly, Delphine; Han, Minyong; Kim, Philip; Steigerwald, Michael L; Roy, Xavier; Nuckolls, Colin

    2016-05-11

    This study describes a new and simple approach to dope two-dimensional transition metal dichalcogenides (TMDCs) using the superatom Co6Se8(PEt3)6 as the electron dopant. Semiconducting TMDCs are wired into field-effect transistor devices and then immersed into a solution of these superatoms. The degree of doping is determined by the concentration of the superatoms in solution and by the length of time the films are immersed in the dopant solution. Using this chemical approach, we are able to turn mono- and few-layer MoS2 samples from moderately to heavily electron-doped states. The same approach applied on WSe2 films changes their characteristics from hole transporting to electron transporting. Moreover, we show that the superatom doping can be patterned on specific areas of TMDC films. To illustrate the power of this technique, we demonstrate the fabrication of a lateral p-n junction by selectively doping only a portion of the channel in a WSe2 device. Finally, encapsulation of the doped films with crystalline hydrocarbon layers stabilizes their properties in an ambient environment. PMID:27082448

  13. Heavy metals influence on ascorbic acid level

    NASA Astrophysics Data System (ADS)

    Kamaldinov, E. V.; Patrashkov, S. A.; Batenyeva, E. V.; Korotkevich, O. S.

    2003-05-01

    It is well known that heavy metals (HM) are extremely dangerous pollutants influencing to metabolism in animals' organisms. The vitamin C is one of the most important metabolites taking part in many biochemical processes. We studied the influence of main essential HM-Zn and Cu as well as the based supertoxical elements - Cd and Pd on ascorbic acid level in serum. The studies were carried out in Tulinskoe farm of Novosibirsk region. The objects of investigations were piglets (2 month after weaning) and 6-month pigs of Early Ripe Meat breed. The levels of HM in bristle were found by stripping voltammetric analysis using the TA-2 analyzer. Vitamin C content was determined by I.P. Kondrakhin (1985) method using 2,2-dipyridyl. The significant negative correlations between Pb, Cd content and vitamin C (-0.46 ± 0.18, -0.47 ± 0.19) in 6-month pigs were determined. The tendencies of negative correlation between all HM levels in hair and ascorbic acid level in plasma of piglets were revealed. Thus, the obtained correlations let us to suppose that all studied HM influence on 1-gulono-gamma-lactone oxidase and other vitamin C metabolism enzymes activity.

  14. Review of 2H-tetraphenylporphyrins metalation in ultra-high vacuum on metal surfaces

    NASA Astrophysics Data System (ADS)

    Panighel, M.; Di Santo, G.; Caputo, M.; Lal, C.; Taleatu, B.; Goldoni, A.

    2013-12-01

    The formation and conformational adaptation of self-assembled monolayer of 2H-tetraphenylporphyrins (2H-TPPs) on metal surfaces, as well as their metalation processes in ultra-high vacuum (UHV), are reviewed. By means of XPS, NEXAFS and STM measurements we demonstrate that, after the annealing at 550 K, a temperature-induced chemical modification of 2H-TPP monolayer on Ag(111) occurs, resulting in the rotation of the phenyl rings parallel to the substrate plane. Moreover, independently of the conformation, we report three different methods to metalate 2H-TPP monolayers in UHV. Experimental evidence indicates that the presence of a metal atom in the TPP macrocycle influences both the conformation of the molecule and its adsorption distance.

  15. Nucleation and growth of noble metals on transition-metal di-tellurides

    NASA Astrophysics Data System (ADS)

    Hla, S. W.; Marinković, V.; Prodan, A.

    1997-04-01

    Transition-metal di-tellurides (α- and β-MoTe 2 and WTe 2) were used as substrates for nucleation and growth studies of noble metals. They represent a group of chemically closely related compounds with different surface topographies. Nucleation and growth of Ag and Au at room temperature were studied by means of UHV-STM, AFM and TEM. The results revealed that the growth and orientation of these metals are influenced by the topography of the substrate surfaces. Contrary to the growth on atomically flat α-MoTe 2, there is an enhanced diffusion and nucleation along the periodic surface troughs on β-MoTe 2 and WTe 2. The topography of their (001) surfaces is responsible for the orientation of metal (112) planes being parallel to the substrate surface.)

  16. Transmission enhancement based on strong interference in metal-semiconductor layered film for energy harvesting

    NASA Astrophysics Data System (ADS)

    Li, Qiang; Du, Kaikai; Mao, Kening; Fang, Xu; Zhao, Ding; Ye, Hui; Qiu, Min

    2016-07-01

    A fundamental strategy to enhance optical transmission through a continuous metallic film based on strong interference dominated by interface phase shift is developed. In a metallic film coated with a thin semiconductor film, both transmission and absorption are simultaneously enhanced as a result of dramatically reduced reflection. For a 50-nm-thick Ag film, experimental transmission enhancement factors of 4.5 and 9.5 are realized by exploiting Ag/Si non-symmetric and Si/Ag/Si symmetric geometries, respectively. These planar layered films for transmission enhancement feature ultrathin thickness, broadband and wide-angle operation, and reduced resistance. Considering one of their potential applications as transparent metal electrodes in solar cells, a calculated 182% enhancement in the total transmission efficiency relative to a single metallic film is expected. This strategy relies on no patterned nanostructures and thereby may power up a wide spectrum of energy-harvesting applications such as thin-film photovoltaics and surface photocatalysis.

  17. Characteristic properties of the Casimir free energy for metal films deposited on metallic plates

    NASA Astrophysics Data System (ADS)

    Klimchitskaya, G. L.; Mostepanenko, V. M.

    2016-04-01

    The Casimir free energy and pressure of thin metal films deposited on metallic plates are considered using the Lifshitz theory and the Drude and plasma model approaches to the role of conduction electrons. The bound electrons are taken into account by using the complete optical data of film and plate metals. It is shown that for films of several tens of nanometers thickness the Casimir free energy and pressure calculated using these approaches differ by hundreds and thousands percent and can be easily discriminated experimentally. According to our results, the free energy of a metal film does not vanish in the limiting case of ideal metal if the Drude model approach is used in contradiction with the fact that the fluctuating field cannot penetrate in its interior. Numerical computations of the Casimir free energy and pressure of Ag and Au films deposited on Cu and Al plates have been performed using both theoretical approaches. It is shown that the free energy of a film can be both negative and positive depending on the metals used. For a Au film on a Ag plate and vice versa the Casimir energy of a film changes its sign with increasing film thickness. Applications of the obtained results for resolving the Casimir puzzle and the problem of stability of thin films are discussed.

  18. Monolayer and/or few-layer graphene on metal or metal-coated substrates

    DOEpatents

    Sutter, Peter Werner; Sutter, Eli Anguelova

    2015-04-14

    Disclosed is monolayer and/or few-layer graphene on metal or metal-coated substrates. Embodiments include graphene mirrors. In an example, a mirror includes a substrate that has a surface exhibiting a curvature operable to focus an incident beam onto a focal plane. A graphene layer conformally adheres to the substrate, and is operable to protect the substrate surface from degradation due to the incident beam and an ambient environment.

  19. Effect of humidity on fretting wear of several pure metals

    NASA Technical Reports Server (NTRS)

    Goto, H.; Buckley, D. H.

    1984-01-01

    Fretting wear experiments with several pure metals were conducted in air at various relative humidity levels. The materials used were iron, aluminum, copper, silver, chromium, titanium, and nickel. Each pure metal had a maximum fretting wear volume at a specific humidity level RH sub max that was not dependent on mechanical factors such as contact load, fretting amplitude, and frequency in the ranges studied. The weight loss due to fretting wear at RH sub max for each pure metal decreased with increasing heat of oxygen adsorption on the metal, indicating that adhesive wear dominated at RH sub max.

  20. Does the Dirac Cone Exist in Silicene on Metal Substrates?

    PubMed Central

    Quhe, Ruge; Yuan, Yakun; Zheng, Jiaxin; Wang, Yangyang; Ni, Zeyuan; Shi, Junjie; Yu, Dapeng; Yang, Jinbo; Lu, Jing

    2014-01-01

    Absence of the Dirac cone due to a strong band hybridization is revealed to be a common feature for epitaxial silicene on metal substrates according to our first-principles calculations for silicene on Ir, Cu, Mg, Au, Pt, Al, and Ag substrates. The destroyed Dirac cone of silicene, however, can be effectively restored with linear or parabolic dispersion by intercalating alkali metal atoms between silicene and the metal substrates, offering an opportunity to study the intriguing properties of silicene without further transfer of silicene from the metal substrates. PMID:24969493

  1. Surface engineering: a low wearing solution for metal-on-metal hip surface replacements.

    PubMed

    Leslie, Ian J; Williams, Sophie; Brown, Chris; Anderson, James; Isaac, Graham; Hatto, Peter; Ingham, Eileen; Fisher, John

    2009-08-01

    Increased patient blood and serum levels of Co and Cr and dissemination of metal wear particles throughout organs and tissues are the primary concerns with metal-on-metal surface replacements. Surface engineering, providing a ceramic bearing surface on a metal substrate, could provide a solution. This study investigated thick (>10 microm) arc evaporation plasma vapor deposition chromium nitride (CrN) coated surface replacements in terms of wear, ion levels, and wear particles in a 10 million cycle hip simulator study, compared to a contemporary metal-on-metal surface replacement. The ion levels were measured by inductively coupled plasma mass spectroscopy. The wear particles were imaged by field emission gun scanning electron microscopy. The CrN-coated bearings had 80% lower wear than the MoM controls. The Cr and Co ion levels in the lubricant of the CrN bearings were 73 and 98% lower than in the MoM controls. The wear particles produced were in the nanometer size range and round to oval in morphology. The CrN coating could provide a reduction in the wear and ion release of MoM surface replacements, thereby reducing the perceived risks to the patient associated with these prostheses. PMID:19195030

  2. Adsorption behavior of heavy metals on biomaterials.

    PubMed

    Minamisawa, Mayumi; Minamisawa, Hiroaki; Yoshida, Shoichiro; Takai, Nobuharu

    2004-09-01

    We have investigated adsorption of Cd(II) and Pb(II) at pH 2-6.7 onto the biomaterials chitosan, coffee, green tea, tea, yuzu, aloe, and Japanese coarse tea, and onto the inorganic adsorbents, activated carbon and zeolite. High adsorptive capabilities were observed for all of the biomaterials at pH 4 and 6.7. In the adsorption of Cd(II), blend coffee, tea, green tea, and coarse tea have comparable loading capacities to activated carbon and zeolite. Although activated carbon, zeolite, and chitosan are utilized in a variety of fields such as wastewater treatment, chemical and metallurgical engineering, and analytical chemistry, these adsorbents are costly. On the other hand, processing of the test biomaterials was inexpensive, and all the biomaterials except for chitosan were able to adsorb large amounts of Pb(II) and Cd(II) ions after a convenient pretreatment of washing with water followed by drying. The high adsorption capability of the biomaterials prepared from plant materials is promising in the development of a novel, low-cost adsorbent. From these results, it is concluded that heavy metal removal using biomaterials would be an effective method for the economic treatment of wastewater. The proposed adsorption method was applied to the determination of amounts of Cd(II) and Pb(II) in water samples. PMID:15373400

  3. Phonon dynamics of graphene on metals.

    PubMed

    Al Taleb, Amjad; Farías, Daniel

    2016-03-16

    The study of surface phonon dispersion curves is motivated by the quest for a detailed understanding of the forces between the atoms at the surface and in the bulk. In the case of graphene, additional motivation comes from the fact that thermal conductivity is dominated by contributions from acoustic phonons, while optical phonon properties are essential to understand Raman spectra. In this article, we review recent progress made in the experimental determination of phonon dispersion curves of graphene grown on several single-crystal metal surfaces. The two main experimental techniques usually employed are high-resolution electron energy loss spectroscopy (HREELS) and inelastic helium atom scattering (HAS). The different dispersion branches provide a detailed insight into the graphene-substrate interaction. Softening of optical modes and signatures of the substrate's Rayleigh wave are observed for strong graphene-substrate interactions, while acoustic phonon modes resemble those of free-standing graphene for weakly interacting systems. The latter allows determining the bending rigidity and the graphene-substrate coupling strength. A comparison between theory and experiment is discussed for several illustrative examples. Perspectives for future experiments are discussed. PMID:26886508

  4. Synthesis of graphitic nanostructures on noble metals

    NASA Astrophysics Data System (ADS)

    Parmentier, Amelie

    In this research, two subjects are studied: the growth of graphene from various catalysts with RF-CVD and the growth of graphitic nanostructures from gold-decorated graphene with RF-CVD. In the first topic, various catalysts are made with magnesium oxide and metal nanoparticles: iron, silver and gold. Using a radio-frequency generator, these catalysts are heated and placed in contact with three gases (argon, hydrogen and methane). By controlling various parameters, graphene synthesis can happen. The results are analyzed with Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Thermo-gravimetrical analysis (TGA), and X-ray diffraction (XRD). In the second topic, commercial graphene is functionalized and decorated with different sizes of gold nanoparticles (1.8nm, 5nm, 10nm and 50nm). Using the RF-CVD process, these samples are heated at different temperatures (500°C, 650°C and 800°C). Depending on the parameters, different kinds of graphitic nanostructures are synthesized. Results are analyzed with Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy.

  5. Phonon dynamics of graphene on metals

    NASA Astrophysics Data System (ADS)

    Taleb, Amjad Al; Farías, Daniel

    2016-03-01

    The study of surface phonon dispersion curves is motivated by the quest for a detailed understanding of the forces between the atoms at the surface and in the bulk. In the case of graphene, additional motivation comes from the fact that thermal conductivity is dominated by contributions from acoustic phonons, while optical phonon properties are essential to understand Raman spectra. In this article, we review recent progress made in the experimental determination of phonon dispersion curves of graphene grown on several single-crystal metal surfaces. The two main experimental techniques usually employed are high-resolution electron energy loss spectroscopy (HREELS) and inelastic helium atom scattering (HAS). The different dispersion branches provide a detailed insight into the graphene-substrate interaction. Softening of optical modes and signatures of the substrate‧s Rayleigh wave are observed for strong graphene-substrate interactions, while acoustic phonon modes resemble those of free-standing graphene for weakly interacting systems. The latter allows determining the bending rigidity and the graphene-substrate coupling strength. A comparison between theory and experiment is discussed for several illustrative examples. Perspectives for future experiments are discussed.

  6. Influence of organic matter transformations on the bioavailability of heavy metals in a sludge based compost.

    PubMed

    Ingelmo, Florencio; Molina, Maria José; Soriano, Maria Desamparados; Gallardo, Antonio; Lapeña, Leonor

    2012-03-01

    The agricultural use of anaerobically digested sewage sludge (ADSS) as stable, mature compost implies knowing its total content in heavy metals and their bioavailability. This depends not only on the initial characteristics of the composted substrates but also on the organic matter transformations during composting which may influence the chemical form of the metals and their bioavailability. The objective of this work was to examine the relationships between the changes in the organic matter content and humus fractions, and the bioavailability of heavy metals. A detailed sampling at 0, 14, 84, and 140 days of the composting process was performed to measure C contents in humic acids (HAs), fulvic acids, (FAs) and humin, the total content of Zn, Pb, Cu, Ni, and Cd, and also their distribution into mobile and mobilisable (MB), and low bioavailability (LB) forms. Significant changes of C contents in HA, FA, and Humin, and in the FA/HA, HA/Humin and C(humus)/TOC ratios were observed during composting. The MB and LB fractions of each metal also varied significantly during composting. The MB fraction increased for Zn, Cu, Ni, and Cd, and the LB fraction increased for Pb. Stepwise linear regressions and quadratic curve estimation conducted on the MB and LB fractions of each metal as dependent on the measured organic variables suggested that Zn bioavailability was mainly associated to percentage of C in FAs. Bioavailability of Cu, Ni and Cd during composting was associated to humin and HAs. Pb concentration increased in the LB form, and its variations followed a quadratic function with the C(humus)/TOC ratio. Our results suggest that the composting process renders the metals in more available forms. The main forms of metal binding in the sludge and their availability in the final compost may be better described when metal fractionation obtained in sequential extraction and humus fractionation during composting are considered together. PMID:21570172

  7. Heavy metal pollution in the soils of various land use types based on physicochemical characteristics.

    PubMed

    Kim, Dong-Su; An, Kwang-Guk; Kim, Ki-Hyun

    2003-05-01

    In this study, soil samples were collected at eight different regional types of Seoul City and analyzed for their physicochemical properties. In addition, the distribution of heavy metal concentrations was analyzed using samples representing both the surface and deep soil layer. The physicochemical properties analyzed for those samples included parameters such as pH, moisture content, apparent (and true) density, pore ratio, solid content, conductivity, ionic strength, total dissolved solid (TDS), total organic carbon (TOC), and total phosphorus (TP). The contents of heavy metal components contained in plant leaves were also analyzed and compared with those measured from different soil layers. Contents of Cu and Cd were highest in the DH area among eight locations investigated and Pb was higher in the surface soil samples of the GS region than any other locations. According to physicochemical properties of the surface and deep soils, acidity was higher in the surface than deep soils. Depending on the selection of treatment method between strong and weak acids, the metal concentrations were larger by 3-5 times in the strong acid than the weak acid treatments. In addition, metals were higher in the deep than in the surface soil and relative metal contents of leaf samples closely resembled those of soil samples. Results of this study suggest that the physicochemical properties of soils determined from different regional types of Seoul area exhibited a close relationship with the land use types and environmental conditions surrounding each region. PMID:12744436

  8. 34 CFR 75.531 - Limit on total cost of a project.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 34 Education 1 2013-07-01 2013-07-01 false Limit on total cost of a project. 75.531 Section 75.531 Education Office of the Secretary, Department of Education DIRECT GRANT PROGRAMS What Conditions Must Be Met by a Grantee? Allowable Costs § 75.531 Limit on total cost of a project. A grantee shall insure...

  9. 34 CFR 75.531 - Limit on total cost of a project.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 34 Education 1 2010-07-01 2010-07-01 false Limit on total cost of a project. 75.531 Section 75.531 Education Office of the Secretary, Department of Education DIRECT GRANT PROGRAMS What Conditions Must Be Met by a Grantee? Allowable Costs § 75.531 Limit on total cost of a project. A grantee shall insure...

  10. 34 CFR 75.531 - Limit on total cost of a project.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 34 Education 1 2014-07-01 2014-07-01 false Limit on total cost of a project. 75.531 Section 75.531 Education Office of the Secretary, Department of Education DIRECT GRANT PROGRAMS What Conditions Must Be Met by a Grantee? Allowable Costs § 75.531 Limit on total cost of a project. A grantee shall insure...

  11. 34 CFR 75.531 - Limit on total cost of a project.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 34 Education 1 2012-07-01 2012-07-01 false Limit on total cost of a project. 75.531 Section 75.531 Education Office of the Secretary, Department of Education DIRECT GRANT PROGRAMS What Conditions Must Be Met by a Grantee? Allowable Costs § 75.531 Limit on total cost of a project. A grantee shall insure...

  12. 34 CFR 75.531 - Limit on total cost of a project.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 34 Education 1 2011-07-01 2011-07-01 false Limit on total cost of a project. 75.531 Section 75.531 Education Office of the Secretary, Department of Education DIRECT GRANT PROGRAMS What Conditions Must Be Met by a Grantee? Allowable Costs § 75.531 Limit on total cost of a project. A grantee shall insure...

  13. Analyses of heavy metals in sewage and sludge from treatment plants in the cities of Campinas and Jaguariúna, using synchrotron radiation total reflection X-rayfluorescence

    NASA Astrophysics Data System (ADS)

    Souza, L. C. F.; Canteras, F. B.; Moreira, S.

    2014-02-01

    A major consequence of accelerated urban and industrial development in the last decades is water pollution. In particular, metal contamination is a significant problem, causing serious changes to the environment and adversely affecting human health. The cities of Campinas and Jaguariúna are inserted in the Campinas Metropolitan Region (CMR), one of the most dynamic regions in the Brazilian economy, accounting for 2.7% of Gross National Product (GNP) and 7.83% of São Paulo State Product—or approximately $ 70.7 billion per year. Besides having a strong economy, the region also presents an infrastructure that provides the development of the entire metropolitan area. Therefore, to study the anthropogenic influences of the cities, the evaluation of the quality of raw and treated effluent and, the sludge generated in sewage treatment plants (STP), especially with regard to heavy metals was performed by Total Reflection X-Ray Fluorescence with Synchrotron Radiation technique. The results were compared with the allowed values established by Brazilian Legislation. For raw and treated effluents collected in Jaguariúna and Campinas city in the Stations of Treatment of Sewage (Camanducaia and Anhumas), Cr presented higher concentrations than the maximum allowed values established by CONAMA 357. However, it is necessary to do other studies to define the fraction of Cr+3 and Cr+6 to compare to the new legislation. The other elements were in agreement with established regulations. For sludge sampled in the same locations, the concentrations of Cr, Cu, Pb, Ni and Zn were compared with the CONAMA 375 and showed values smaller than the maximum allowed values, indicating the possibility to re-use the sludge.

  14. Graphene nucleation on transition metal surface: structure transformation and role of the metal step edge.

    PubMed

    Gao, Junfeng; Yip, Joanne; Zhao, Jijun; Yakobson, Boris I; Ding, Feng

    2011-04-01

    The nucleation of graphene on a transition metal surface, either on a terrace or near a step edge, is systematically explored using density functional theory calculations and applying the two-dimensional (2D) crystal nucleation theory. Careful optimization of the supported carbon clusters, C(N) (with size N ranging from 1 to 24), on the Ni(111) surface indicates a ground state structure transformation from a one-dimensional C chain to a 2D sp(2) C network at N ≈ 10-12. Furthermore, the crucial parameters controlling graphene growth on the metal surface, nucleation barrier, nucleus size, and nucleation rate on a terrace or near a step edge are calculated. In agreement with numerous experimental observations, our analysis shows that graphene nucleation near a metal step edge is superior to that on a terrace. On the basis of our analysis, we propose the use of graphene seeds to synthesize high-quality graphene in large area. PMID:21384854

  15. Interference of salts used on aqueous two-phase systems on the quantification of total proteins.

    PubMed

    Golunski, Simone Maria; Sala, Luisa; Silva, Marceli Fernandes; Dallago, Rogério Marcos; Mulinari, Jéssica; Mossi, Altemir José; Brandelli, Adriano; Kalil, Susana Juliano; Di Luccio, Marco; Treichel, Helen

    2016-02-01

    In this study the interference of potassium phosphate, sodium citrate, sodium chloride and sodium nitrate salts on protein quantification by Bradford's method was assessed. Potassium phosphate and sodium citrate salts are commonly used in aqueous two-phase systems for enzyme purification. Results showed that the presence of potassium phosphate and sodium citrate salts increase the absorbance of the samples, when compared with the samples without any salt. The increase in absorptivity of the solution induces errors on protein quantification, which are propagated to the calculations of specific enzyme activity and consequently on purification factor. The presence of sodium chloride and sodium nitrate practically did not affect the absorbance of inulinase, probably the metals present in the enzyme extract did not interact with the added salts. PMID:26616454

  16. Photobiont diversity in lichens from metal-rich substrata based on ITS rDNA sequences.

    PubMed

    Backor, Martin; Peksa, Ondrej; Skaloud, Pavel; Backorová, Miriam

    2010-05-01

    The photobiont is considered as the more sensitive partner of lichen symbiosis in metal pollution. For this reason the presence of a metal tolerant photobiont in lichens may be a key factor of ecological success of lichens growing on metal polluted substrata. The photobiont inventory was examined for terricolous lichen community growing in Cu mine-spoil heaps derived by historical mining. Sequences of internal transcribed spacer (ITS) were phylogenetically analyzed using maximum likelihood analyses. A total of 50 ITS algal sequences were obtained from 22 selected lichen taxa collected at three Cu mine-spoil heaps and two control localities. Algae associated with Cladonia and Stereocaulon were identified as members of several Asterochloris lineages, photobionts of cetrarioid lichens clustered with Trebouxia hypogymniae ined. We did not find close relationship between heavy metal content (in localities as well as lichen thalli) and photobiont diversity. Presence of multiple algal genotypes in single lichen thallus has been confirmed. PMID:20031214

  17. Molten metal-related ocular thermal burn: report on two cases.

    PubMed

    Arici, Ceyhun; Iskeleli, Guzin; Atalay, Eray; Mangan, Mehmet Serhat; Kilic, Belgin

    2015-01-01

    We report two cases of severe thermal burns on the ocular surface and its adnexal appendages that developed secondary to exposure to molten heavy metal with a melting temperature of near-thousand degree Celsius. Despite aggressive intervention and strict monitoring, the profound inflammation caused significant damage to the ocular surface, ending up in an intractable infection with an unfavorable outcome. The heat of the molten metal at impact, the heat-retaining capacity of the heavy metal, the total area of the ocular surface exposed to the molten metal, and the duration of exposure determined the severity of the injury. The unfavorable outcome, despite an intensive treatment, in terms of visual acuity and cosmetic appearance, should be explicitly explained to the patient, and a psychiatrist consultation should be considered if necessary. PMID:26677043

  18. Influence of acid volatile sulfides and metal concentrations on metal partitioning in contaminated sediments

    USGS Publications Warehouse

    Lee, J.-S.; Lee, B.-G.; Luoma, S.N.; Choi, H.J.; Koh, C.-H.; Brown, C.L.

    2000-01-01

    The influence of acid volatile sulfide (AVS) on the partitioning of Cd, Ni, and Zn in porewater (PW) and sediment as reactive metals (SEM, simultaneously extracted metals) was investigated in laboratory microcosms. Two spiking procedures were compared, and the effects of vertical geochemical gradients and infaunal activity were evaluated. Sediments were spiked with a Cd-Ni-Zn mixture (0.06, 3, 7.5 ??mol/g, respectively) containing four levels of AVS (0.5, 7.5, 15, 35 ??mol/g). The results were compared to sediments spiked with four levels of Cd-Ni-Zn mixtures at one AVS concentration (7.5 ??mol/g). A vertical redox gradient was generated in each treatment by an 18-d incubation with an oxidized water column. [AVS] in the surface sediments decreased by 65-95% due to oxidation during incubation; initial [AVS] was maintained at 0.5-7.5 cm depth. PW metal concentrations were correlated with [SEM - AVS] among all data. But PW metal concentrations were variable, causing the distribution coefficient, Kd(pw) (the ratio of [SEM] to PW metal concentrations) to vary by 2-3 orders of magnitude at a given [SEM - AVS]. One reason for the variability was that vertical profiles in PW metal concentrations appeared to be influenced by diffusion as well as [SEM - AVS]. The presence of animals appeared to enhance the diffusion of at least Zn. The generalization that PW metal concentrations are controlled by [SEM - AVS] is subject to some important qualifications if vertical gradients are complicated, metal concentrations vary, or equilibration times differ.The influence of acid volatile sulfide (AVS) on the partitioning of Cd, Ni, and Zn in porewater (PW) and sediment as reactive metals (SEM, simultaneously extracted metals) was investigated in laboratory microcosms. Two spiking procedures were compared, and the effects of vertical geochemical gradients and infaunal activity were evaluated. Sediments were spiked with a Cd-Ni-Zn mixture (0.06, 3, 7.5 ??mol/g, respectively) containing

  19. Total Geomagnetic Survey on Suruga Bay, on the Pacific cost, Shizuoka, Japan, the second series report.

    NASA Astrophysics Data System (ADS)

    Ichinose, S.; Baba, H.

    2015-12-01

    In 2009 to 2014, total geomagnetic and geological surveys by School of Marine Science & Technology, Tokai University, were conducted on Suruga Bay, located on the Pacific coast of Honshu in Shizuoka Prefecture, central Japan, where a large thrust earthquake, often referred to as the Tokai earthquake, has been supposed to occur soon (Ishibashi, 1981). Suruga Bay area, where the Philippine Sea plate subducts beneath Japan, had some local magnetic anomalies on the overriding plate side. The past investigation of ship-borne survey conducted in Suruga Bay area is geomagnetic anomaly data of the Hydrographic Department of the Maritime Safety Agency in 1997. Detailed geomagnetic surveys carried out in the Suruga Bay area, is 50 km x 35km in S-N and W-E, respectively. Total geomagnetic anomaly values range from +100nT to +600nT. In this report, we carried out newly geomagnetic survey lines which costal region on Suruga Bay. The following results were found. (1) The costal region of Izu Peninsula in Northern part of Izu-Ogasawara arc is indicated high geomagnetic anomaly. This cause is regarded as something to come near to some volcanos. (2) And costal region of the Fujigawa fault system in the Sourath Fossa Magna region is indicated high geomagnetic anomaly. We present features of total geomagnetic anomalies on and around Suruga Bay with the results of inversion.

  20. Metal ion levels and functional results after either resurfacing hip arthroplasty or conventional metal-on-metal hip arthroplasty

    PubMed Central

    2011-01-01

    Background Modern metal-on-metal hip resurfacing was introduced as a bone-preserving method of joint reconstruction for young and active patients; however, the large diameter of the bearing surfaces is of concern for potentially increased metal ion release. Patients and methods 71 patients (< 65 years old) were randomly assigned to receive either a resurfacing (R) hip arthroplasty (n = 38) or a conventional metal-on-metal (C) hip arthroplasty (n = 33). Functional outcomes were assessed preoperatively and at 6, 12, and 24 months. Cobalt and chromium blood levels were analyzed preoperatively and at 3, 6, 12, and 24 months. Results All functional outcome scores improved for both groups. At 12 and 24 months, the median UCLA activity score was 8 in the R patients and 7 in the C patients (p < 0.05). At 24 months, OHS was median 16 in C patients and 13 in R patients (p < 0.05). However, in spite of randomization, UCLA scores also appeared to be higher in R patients at baseline. Satisfaction was similar in both groups at 24 months. Cobalt concentrations were statistically significantly higher for R patients only at 3 and 6 months. Chromium levels remained significantly higher for R patients until 24 months. No pseudotumors were encountered in either group. One R patient was revised for early aseptic loosening and in 2 C patients a cup insert was exchanged for recurrent dislocation. Interpretation R patients scored higher on UCLA, OHS, and satisfaction at some time points; however, as for the UCLA, preoperative levels were already in favor of R. The differences, although statistically significant, were of minor clinical importance. Chromium blood levels were statistically significantly higher for R patients at all follow-up measurements, whereas for cobalt this was only observed up to 6 months. The true value of resurfacing hip arthroplasty over conventional metal-on-metal hip arthroplasty will be determined by longer follow-up and a possible shift of balance between their

  1. Metallic glass ingots based on yttrium

    NASA Astrophysics Data System (ADS)

    Guo, Faqiang; Poon, S. Joseph; Shiflet, Gary J.

    2003-09-01

    We report a family of yttrium metallic alloys that are able to form glassy ingots directly from the liquid, as well as forming bulk-sized amorphous rods with diameters over 2 cm by water cooling of the alloy melt sealed in quartz tubes. It is apparent that, in addition to the strong chemical interaction among the components, the simultaneous occurrence of well-distributed atom sizes and a strongly depressed liquidus temperature in multicomponent metallic alloys is responsible for the formation of glassy ingots.

  2. Effects of total solids content on waste activated sludge thermophilic anaerobic digestion and its sludge dewaterability.

    PubMed

    Wang, Tianfeng; Chen, Jie; Shen, Honglang; An, Dong

    2016-10-01

    The role of total solids content on sludge thermophilic anaerobic digestion was investigated in batch reactors. A range of total solids content from 2% to 10% was evaluated with two replicates. The lowest inhibitory concentration for free ammonia and total ammonia of sludge thermophilic anaerobic digestion was 110.9-171.4mg/L and 1313.1-1806.7mg/L, respectively. The volumetric biogas production rate increased with increasing of total solids content, but the corresponding biogas yield per gram volatile solid decreased. The result of normalized capillary suction time indicated that the dewaterability of digested sludge at high total solids content was poor, while solid content of sediment obtained by centrifuging sludge at 2000g for 10min increased with increasing of total solids content of sludge. The results suggest that thickened sludge mixed with dewatered sludge at an appropriate ratio could get high organic loading rate, high biogas yield and adequate dewatering effort. PMID:26897469

  3. Some Case Studies on Metal-Microbe Interactions to Remediate Heavy Metals- Contaminated Soils in Korea

    NASA Astrophysics Data System (ADS)

    Chon, Hyo-Taek

    2015-04-01

    Conventional physicochemical technologies to remediate heavy metals-contaminated soil have many problems such as low efficiency, high cost and occurrence of byproducts. Recently bioremediation technology is getting more and more attention. Bioremediation is defined as the use of biological methods to remediate and/or restore the contaminated land. The objectives of bioremediation are to degrade hazardous organic contaminants and to convert hazardous inorganic contaminants to less toxic compounds of safe levels. The use of bioremediation in the treatment of heavy metals in soils is a relatively new concept. Bioremediation using microbes has been developed to remove toxic heavy metals from contaminated soils in laboratory scale to the contaminated field sites. Recently the application of cost-effective and environment-friendly bioremediation technology to the heavy metals-contaminated sites has been gradually realized in Korea. The merits of bioremediation include low cost, natural process, minimal exposure to the contaminants, and minimum amount of equipment. The limitations of bioremediation are length of remediation, long monitoring time, and, sometimes, toxicity of byproducts for especially organic contaminants. From now on, it is necessary to prove applicability of the technologies to contaminated sites and to establish highly effective, low-cost and easy bioremediation technology. Four categories of metal-microbe interactions are generally biosorption, bioreduction, biomineralization and bioleaching. In this paper, some case studies of the above metal-microbe interactions in author's lab which were published recently in domestic and international journals will be introduced and summarized.

  4. Total Geomagnetic Survey on Suruga Bay, on the Pacific cost, Shizuoka, Japan

    NASA Astrophysics Data System (ADS)

    Baba, H.; Ishida, M.; Sakamoto, I.; Onishi, N.

    2012-12-01

    In 2009 to 2012, total geomagnetic and geological surveys by School of Marine Science & Technology, Tokai University, were conducted on Suruga Bay, located on the Pacific coast of Honshu in Shizuoka Prefecture, central Japan, where a large thrust earthquake, often referred to as the Tokai earthquake, has been supposed to occur soon (Ishibashi, 1981). Suruga Bay area, where the Philippine Sea plate subducts beneath Japan, had some local magnetic anomalies on the overriding plate side. The past investigation of ship-borne survey conducted in Suruga Bay area is geomagnetic anomaly data of the Hydrographic Department of the Maritime Safety Agency in 1997. Detailed geomagnetic surveys carried out in the Suruga Bay area, is 50 km x 35km in S-N and W-E, respectively. Total geomagnetic anomaly values range from +100nT to +600nT. We carried out 2.5d inversion analyses for some positive high anomalies to reveal the dimensions of anomalous body, assuming uniformly magnetization. We present features of total geomagnetic anomalies on and around Suruga Bay with the results of inversion.

  5. Nanosecond pulsed laser generation of holographic structures on metals

    NASA Astrophysics Data System (ADS)

    Wlodarczyk, Krystian L.; Ardron, Marcus; Weston, Nick J.; Hand, Duncan P.

    2016-03-01

    A laser-based process for the generation of phase holographic structures directly onto the surface of metals is presented. This process uses 35ns long laser pulses of wavelength 355nm to generate optically-smooth surface deformations on a metal. The laser-induced surface deformations (LISDs) are produced by either localized laser melting or the combination of melting and evaporation. The geometry (shape and dimension) of the LISDs depends on the laser processing parameters, in particular the pulse energy, as well as on the chemical composition of a metal. In this paper, we explain the mechanism of the LISDs formation on various metals, such as stainless steel, pure nickel and nickel-chromium Inconel® alloys. In addition, we provide information about the design and fabrication process of the phase holographic structures and demonstrate their use as robust markings for the identification and traceability of high value metal goods.

  6. Stereochemical Recognition of Helicenes on Metal Surfaces.

    PubMed

    Ernst, Karl-Heinz

    2016-06-21

    The chiral recognition among biomolecules is fundamentally important for many processes of life, including the stereochemistry of evolution. Of special interest is chiral recognition during crystallization of racemates, when either homochiral recognition leads to a conglomerate of homochiral crystals or heterochiral recognition dominates resulting in a racemic compound. The complex nature of molecular recognition at the level of nucleation and crystal growth renders it difficult to understand and calls for manageable model systems. Notably, the approach of studying aggregation of molecules at surfaces under well-defined conditions includes the benefit of the availability of a multitude of highly sensitive investigation methods, of which scanning tunneling microscopy (STM) with its submolecular resolution is tremendously valuable. Heterogeneous nucleation at surfaces is strongly favored over homogeneous nucleation in solution; hence, surfaces are significantly involved in stereochemical recognition during crystallization. Helicenes are a fascinating class of chiral compounds with outstanding optical activity. These π-conjugated, ortho-fused, aromatic hydrocarbons are promising candidates for organic electronic devices such as sensors, circular dichroic photonics, liquid crystal displays or spin filters. But in particular the defined footprint of their terminal benzo rings on a surface makes them interesting for studying stereochemical recognition with different single crystalline surfaces and the impact this has, in turn, on intermolecular recognition. In this Account, we describe the self-assembly of helicenes on metal surfaces with the focus on stereochemical recognition in two-dimensional structures. Using the isomeric all-carbon helicenes, heptahelicene and dibenzohelicene as examples, different aggregation phenomena on different surfaces of single crystalline copper, silver, and gold are investigated. By means of STM different modes of transmission of

  7. Total Hip Arthroplasty Using Modular Trabecular Metal Acetabular Components for Failed Treatment of Acetabular Fractures: A Mid-term Follow-up Study

    PubMed Central

    Huang, De-Yong; Zhang, Liang; Zhou, Yi-Xin; Zhang, Chun-Yu; Xu, Hui; Huang, Yong

    2016-01-01

    Background: Porous-coated cups have been widely used in acetabular reconstruction after failed treatment of acetabular fractures, and good results have been reported with the use of these cups; however, the durability and functionality of modular trabecular metal (TM) acetabular components in acetabular reconstruction after failed treatment of acetabular fractures remain unclear. This study aimed to examine the radiographic and clinical outcomes associated with the use of modular TM acetabular components for failed treatment of acetabular fractures to assess the durability and functionality of these components in acetabular reconstruction after failed treatment of acetabular fractures. Methods: A total of 41 patients (41 hips) underwent total hip arthroplasty (THA) using modular TM acetabular components for failed treatment of acetabular fractures at our hospital between January 2007 and December 2012. Among these patients, two were lost to follow-up. Therefore, 39 patients (39 hips) were finally included in this study. The Harris hip score before and after the surgery, satisfaction level of the patients, and radiographic results were assessed. Results: The mean Harris hip score increased from 34 (range, 8–52) before surgery to 91 (range, 22–100) at the latest follow-up examination (P < 0.001). The results were excellent for 28 hips, good for six, fair for three, and poor for two. Among the 39 patients, 25 (64%) and 10 (26%) were very satisfied and somewhat satisfied, respectively. All cups were found to be fully incorporated, and no evidence of cup migration or periacetabular osteolysis was noted. Conclusions: Despite the technically demanding nature of the procedure, THA using modular TM acetabular components showed good durability and functionality and may be an effective reconstruction option for failed treatment of acetabular fractures. PMID:27064033

  8. Anisotropic metal growth on phospholipid nanodiscs via lipid bilayer expansion

    NASA Astrophysics Data System (ADS)

    Oertel, Jana; Keller, Adrian; Prinz, Julia; Schreiber, Benjamin; Hübner, René; Kerbusch, Jochen; Bald, Ilko; Fahmy, Karim

    2016-05-01

    Self-assembling biomolecules provide attractive templates for the preparation of metallic nanostructures. However, the intuitive transfer of the “outer shape” of the assembled macromolecules to the final metallic particle depends on the intermolecular forces among the biomolecules which compete with interactions between template molecules and the metal during metallization. The shape of the bio-template may thus be more dynamic than generally assumed. Here, we have studied the metallization of phospholipid nanodiscs which are discoidal particles of ~10 nm diameter containing a lipid bilayer ~5 nm thick. Using negatively charged lipids, electrostatic adsorption of amine-coated Au nanoparticles was achieved and followed by electroless gold deposition. Whereas Au nanoparticle adsorption preserves the shape of the bio-template, metallization proceeds via invasion of Au into the hydrophobic core of the nanodisc. Thereby, the lipidic phase induces a lateral growth that increases the diameter but not the original thickness of the template. Infrared spectroscopy reveals lipid expansion and suggests the existence of internal gaps in the metallized nanodiscs, which is confirmed by surface-enhanced Raman scattering from the encapsulated lipids. Interference of metallic growth with non-covalent interactions can thus become itself a shape-determining factor in the metallization of particularly soft and structurally anisotropic biomaterials.

  9. Anisotropic metal growth on phospholipid nanodiscs via lipid bilayer expansion.

    PubMed

    Oertel, Jana; Keller, Adrian; Prinz, Julia; Schreiber, Benjamin; Hübner, René; Kerbusch, Jochen; Bald, Ilko; Fahmy, Karim

    2016-01-01

    Self-assembling biomolecules provide attractive templates for the preparation of metallic nanostructures. However, the intuitive transfer of the "outer shape" of the assembled macromolecules to the final metallic particle depends on the intermolecular forces among the biomolecules which compete with interactions between template molecules and the metal during metallization. The shape of the bio-template may thus be more dynamic than generally assumed. Here, we have studied the metallization of phospholipid nanodiscs which are discoidal particles of ~10 nm diameter containing a lipid bilayer ~5 nm thick. Using negatively charged lipids, electrostatic adsorption of amine-coated Au nanoparticles was achieved and followed by electroless gold deposition. Whereas Au nanoparticle adsorption preserves the shape of the bio-template, metallization proceeds via invasion of Au into the hydrophobic core of the nanodisc. Thereby, the lipidic phase induces a lateral growth that increases the diameter but not the original thickness of the template. Infrared spectroscopy reveals lipid expansion and suggests the existence of internal gaps in the metallized nanodiscs, which is confirmed by surface-enhanced Raman scattering from the encapsulated lipids. Interference of metallic growth with non-covalent interactions can thus become itself a shape-determining factor in the metallization of particularly soft and structurally anisotropic biomaterials. PMID:27216789

  10. Anisotropic metal growth on phospholipid nanodiscs via lipid bilayer expansion

    PubMed Central

    Oertel, Jana; Keller, Adrian; Prinz, Julia; Schreiber, Benjamin; Hübner, René; Kerbusch, Jochen; Bald, Ilko; Fahmy, Karim

    2016-01-01

    Self-assembling biomolecules provide attractive templates for the preparation of metallic nanostructures. However, the intuitive transfer of the “outer shape” of the assembled macromolecules to the final metallic particle depends on the intermolecular forces among the biomolecules which compete with interactions between template molecules and the metal during metallization. The shape of the bio-template may thus be more dynamic than generally assumed. Here, we have studied the metallization of phospholipid nanodiscs which are discoidal particles of ~10 nm diameter containing a lipid bilayer ~5 nm thick. Using negatively charged lipids, electrostatic adsorption of amine-coated Au nanoparticles was achieved and followed by electroless gold deposition. Whereas Au nanoparticle adsorption preserves the shape of the bio-template, metallization proceeds via invasion of Au into the hydrophobic core of the nanodisc. Thereby, the lipidic phase induces a lateral growth that increases the diameter but not the original thickness of the template. Infrared spectroscopy reveals lipid expansion and suggests the existence of internal gaps in the metallized nanodiscs, which is confirmed by surface-enhanced Raman scattering from the encapsulated lipids. Interference of metallic growth with non-covalent interactions can thus become itself a shape-determining factor in the metallization of particularly soft and structurally anisotropic biomaterials. PMID:27216789

  11. 20 CFR 404.1911 - Effects of a totalization agreement on entitlement to hospital insurance benefits.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... entitlement to hospital insurance benefits. 404.1911 Section 404.1911 Employees' Benefits SOCIAL SECURITY ADMINISTRATION FEDERAL OLD-AGE, SURVIVORS AND DISABILITY INSURANCE (1950- ) Totalization Agreements Benefit Provisions § 404.1911 Effects of a totalization agreement on entitlement to hospital insurance benefits....

  12. CARTILAGE-ON-CARTILAGE VS. METAL-ON-CARTILAGE IMPACT CHARACTERISTICS AND RESPONSES

    PubMed Central

    Heiner, Anneliese D.; Smith, Abigail D.; Goetz, Jessica E.; Goreham-Voss, Curtis M.; Judd, Kyle T.; McKinley, Todd O.; Martin, James A.

    2013-01-01

    A common in vitro model for studying acute mechanical damage in cartilage is to impact an isolated osteochondral or cartilage specimen with a metallic impactor. The mechanics of a cartilage-on-cartilage (COC) impact, as encountered in vivo, are likely different than those of a metal-on-cartilage (MOC) impact. The hypothesis of this study was that impacted in vitro COC and MOC specimens would differ in their impact behavior, mechanical properties, chondrocyte viability, cell metabolism, and histologic structural damage. Osteochondral specimens were impacted with either an osteochondral plug or a metallic cylinder at the same delivered impact energy per unit area, and processed after 14 days in culture. The COC impacts resulted in about half of the impact maximum stress and a quarter of the impact maximum stress rate of change, as compared to the MOC impacts. The impacted COC specimens had smaller changes in mechanical properties, smaller decreases in chondrocyte viability, higher total proteoglycan content, and less histologic structural damage, as compared to the impacted MOC specimens. If metal-on-cartilage impact conditions are to be used for modeling of articular injuries and post-traumatic osteoarthritis, the differences between COC and MOC impacts must be kept in mind. PMID:23335281

  13. Pendant-Drop Surface-Tension Measurement On Molten Metal

    NASA Technical Reports Server (NTRS)

    Man, Kin Fung; Thiessen, David

    1996-01-01

    Method of measuring surface tension of molten metal based on pendant-drop method implemented in quasi-containerless manner and augmented with digital processing of image data. Electrons bombard lower end of sample rod in vacuum, generating hanging drop of molten metal. Surface tension of drop computed from its shape. Technique minimizes effects of contamination.

  14. Metal Nanostructure Formation on Graphene: Weak versus Strong Bonding

    SciTech Connect

    Hupalo, Myron; Liu, Xiaojie; Wang, Cai-Zhuang; Lu, Wen-Cai; Yao, Yon-Xin; Ho, Kai-Ming; Tringides, Michael C.

    2011-05-10

    Graphene is an exciting material with numerous potential applications. To understand metal graphene interaction two different metals were studied. Two large Pb islands nucleate at 78K indicating fast diffusion and weak interaction(right). On the contrary, for Dysprosium a high island density is observed confirming slow diffusion and strong interaction(left).

  15. Bacterial Exopolysaccharides For Corrosion Inhibition on Metal Substrates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biofilms, composed of extra-cellular polymers secreted by bacteria, have been observed to both increase as well as decrease the rate of metal corrosion. Exopolysaccharides derived from Leuconostoc mesenteroides cultures have been shown to inhibit corrosion on corrosion-sensitive metals. The substa...

  16. SOIL MICROBIAL EFFECTS ON HEAVY METAL UPTAKE INTO HYPERACCUMULATORS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Uptake of heavy metals into hyperaccumulators is influenced by a number of chemical, physical and biological factors. Of these, recent evidence has shown that microbes living within the rhizosphere of hyperaccumulators may have a significant effect on metal uptake. Much is known about the role my...

  17. Effects of metals on a range of Streptomyces species

    SciTech Connect

    Abbas, A.; Edwards, C. )

    1989-08-01

    A plate diffusion method was used to assess the tolerance of 28 mesophilic and 4 thermophilic species of streptomyces to eight metals. This method allowed a qualitative screen of the effects of the metals on growth, on sporulation, and in some cases, on secondary metabolite production. Tolerant and sensitive species were identified, some of which exhibited the same response (i.e., tolerance or sensitivity) to a number of metals. Experiments in liquid culture were used to quantify the precise concentration ranges of the metals at which the most tolerant or sensitive species could grow. Distribution profiles of the sensitivities of all species examined toward different metals revealed that the order of toxicity was Hg > Cd > Co > Zn > Ni > Cu > Cr > Mn.

  18. Risks of using membrane filtration for trace metal analysis and assessing the dissolved metal fraction of aqueous media--a study on zinc, copper and nickel.

    PubMed

    Hedberg, Yolanda; Herting, Gunilla; Wallinder, Inger Odnevall

    2011-05-01

    Membrane filtration is commonly performed for solid-liquid separation of aqueous solutions prior to trace metal analysis and when assessing "dissolved" metal fractions. Potential artifacts induced by filtration such as contamination and/or adsorption of metals within the membrane have been investigated for different membrane materials, metals, applied pressures and pre-cleaning steps. Measurements have been conducted on aqueous solutions including well-defined metal standards, ultrapure water, and on runoff water from corroded samples. Filtration using both non-cleaned and pre-cleaned filters revealed contamination and adsorption effects, in particular pronounced for zinc, evident for copper but non-significant for nickel. The results clearly show these artifacts to be non-systematic both for non-cleaned and pre-cleaned membranes. The applied pressure was of minor importance. Measurements of the labile fraction by means of stripping voltammetry clearly elucidate that membrane filtration followed by total metal analysis cannot accurately assess the labile or the dissolved metal fraction. PMID:21367497

  19. Meeting the demands of on-going metal-on-metal hip surveillance through nurse led services.

    PubMed

    Elliott, Sue; Langfield, Sarah

    2016-02-01

    This paper discusses the implications following a recall of all metal-on-metal hip replacements by the Medicines and Healthcare products regulatory Agency (MHRA). Issues identified were the release of metal ions from the metal implants. These ions were found to seep into local tissues and cause reactions that destroyed muscle and bone leaving some patients with long term disability. At the centre surveillance was monitored by an extension of the current Nurse Led services using existing staff and resources. There were a significant number of patients that required monitoring and there were difficulties contacting these patients and ensuring that they understood the importance of attending a clinic. PMID:26772766

  20. Comparative toxicity of five metals on various biological subjects

    SciTech Connect

    Fargasova, A. )

    1994-08-01

    Environmental contaminants, including metals, can have toxic effects on many different organisms and affect biological processes at cellular, population, community and ecosystem levels of organization. Metals are of particular interest because they may have a positive effect as micronutrients at low concentrations as well as a toxic effect at higher levels. Numerous efforts have been made to correlate and predict metal-ion toxicities on various aquatic and terrestrial species, according to the physical and chemical properties of the metals. The acute and chronic toxicities of metals have been studied on many freshwater organisms and also on plants. The water flea, Daphnia magna, an important freshwater zooplankter, is a useful test species to study sensitivity to environmental toxicants and has been recognized as a general representative for other freshwater animals. As Khangarot described, little information is available on the effects of metals to tubificid worms, which are widely distributed in the aquatic environment and are useful indicators of varying degrees of aquatic pollution. Most recent hazard evaluation programs recommend algal toxicity tests for initial evaluations of chemicals that are expected to reach surface waters and that have suspected or unknown phytotoxic properties. For higher plants, the accumulation of metals, especially cadmium, was tested when plants grew in sewage sludge-amended soils or in soils of cadmium residues form phosphate fertilizers. No reports were available indicating the effects of these metals on seed germination and root growth. This study was conducted to determine the acute toxicological effects of some metals (As, Pb, Cr, Hg, Cd) on four biological subjects (tubificid worms, Daphnia magna sp., Scenedesmus quadricauda, seeds of Sinapis alba) and to compare their sensitivity to individual test metals. 16 refs., 1 tab.

  1. A simulator study of adverse wear with metal and cement debris contamination in metal-on-metal hip bearings

    PubMed Central

    Halim, T.; Clarke, I. C.; Burgett-Moreno, M. D.; Donaldson, T. K.; Savisaar, C.; Bowsher, J. G.

    2015-01-01

    Objectives Third-body wear is believed to be one trigger for adverse results with metal-on-metal (MOM) bearings. Impingement and subluxation may release metal particles from MOM replacements. We therefore challenged MOM bearings with relevant debris types of cobalt–chrome alloy (CoCr), titanium alloy (Ti6Al4V) and polymethylmethacrylate bone cement (PMMA). Methods Cement flakes (PMMA), CoCr and Ti6Al4V particles (size range 5 µm to 400 µm) were run in a MOM wear simulation. Debris allotments (5 mg) were inserted at ten intervals during the five million cycle (5 Mc) test. Results In a clean test phase (0 Mc to 0.8 Mc), lubricants retained their yellow colour. Addition of metal particles at 0.8 Mc turned lubricants black within the first hour of the test and remained so for the duration, while PMMA particles did not change the colour of the lubricant. Rates of wear with PMMA, CoCr and Ti6Al4V debris averaged 0.3 mm3/Mc, 4.1 mm3/Mc and 6.4 mm3/Mc, respectively. Conclusions Metal particles turned simulator lubricants black with rates of wear of MOM bearings an order of magnitude higher than with control PMMA particles. This appeared to model the findings of black, periarticular joint tissues and high CoCr wear in failed MOM replacements. The amount of wear debris produced during a 500 000-cycle interval of gait was 30 to 50 times greater than the weight of triggering particle allotment, indicating that MOM bearings were extremely sensitive to third-body wear. Cite this article: Bone Joint Res 2015;4:29–37. PMID:25736072

  2. Growth morphology and properties of metals on graphene

    DOE PAGESBeta

    Liu, Xiaojie; Han, Yong; Evans, James W.; Engstfeld, Albert K.; Behm, R. Juergen; Tringides, Michael C.; Hupalo, Myron; Lin, Hai -Qing; Huang, Li; Ho, Kai -Ming; et al

    2015-12-01

    Graphene, a single atomic layer of graphite, has been the focus of recent intensive studies due to its novel electronic and structural properties. With this study, metals grown on graphene also have been of interest because of their potential use as metal contacts in graphene devices, for spintronics applications, and for catalysis. All of these applications require good understanding and control of the metal growth morphology, which in part reflects the strength of the metal–graphene bond. The interaction between graphene and metal is sufficiently strong to modify the electronic structure of graphene is also of great importance. We will discussmore » recent experimental and computational studies related to deposition of metals on graphene supported on various substrates (SiC, SiO2, and hexagonal close-packed metal surfaces). Of specific interest are the metal–graphene interactions (adsorption energies and diffusion barriers of metal adatoms), and the crystal structures and thermal stability of the metal nanoclusters.« less

  3. The Influence Of Component Alignment On The Life Of Total Knee Prostheses

    NASA Astrophysics Data System (ADS)

    Bugariu, Delia; Bereteu, Liviu

    2012-12-01

    An arthritic knee affects the patient's life by causing pain and limiting movement. If the cartilage and the bone surfaces are severely affected, the natural joint is replaced with an artificial joint. The procedure is called total knee arthroplasty (TKA). Lately, the numbers of implanted total knee prostheses grow steadily. An important factor in TKA is the perfect alignment of the total knee prosthesis (TKP) components. Component misalignment can lead to the prosthesis loss by producing wear particles. The paper proposes a study on mechanical behaviors of a TKP based on numerical analysis, using ANSYS software. The numerical analysis is based on both the normal and the changed angle of the components alignment.

  4. Growth of transition metals on cerium tungstate model catalyst layers.

    PubMed

    Skála, T; Tsud, N; Stetsovych, V; Mysliveček, J; Matolín, V

    2016-10-01

    Two model catalytic metal/oxide systems were investigated by photoelectron spectroscopy and scanning tunneling microscopy. The mixed-oxide support was a cerium tungstate epitaxial thin layer grown in situ on the W(1 1 0) single crystal. Active particles consisted of palladium and platinum 3D islands deposited on the tungstate surface at 300 K. Both metals were found to interact weakly with the oxide support and the original chemical state of both support and metals was mostly preserved. Electronic and morphological changes are discussed during the metal growth and after post-annealing at temperatures up to 700 K. Partial transition-metal coalescence and self-cleaning from the CO and carbon impurities were observed. PMID:27494195

  5. Asymmetric light reflectance from metal nanoparticle arrays on dielectric surfaces

    PubMed Central

    Huang, K.; Pan, W.; Zhu, J. F.; Li, J. C.; Gao, N.; Liu, C.; Ji, L.; Yu, E. T.; Kang, J.Y.

    2015-01-01

    Asymmetric light reflectance associated with localized surface plasmons excited in metal nanoparticles on a quartz substrate is observed and analyzed. This phenomenon is explained by the superposition of two waves, the wave reflected by the air/quartz interface and that reflected by the metal nanoparticles, and the resulting interference effects. Far field behavior investigation suggests that zero reflection can be achieved by optimizing the density of metal nanoparticles. Near field behavior investigation suggests that the coupling efficiency of localized surface plasmon can be additionally enhanced by separating the metal NPs from substrates using a thin film with refractive index smaller than the substrate. The latter behavior is confirmed via surface-enhanced Raman spectroscopy studies using metal nanoparticles on Si/SiO2 substrates. PMID:26679353

  6. Silicide coating on refractory metals in molten salt

    NASA Astrophysics Data System (ADS)

    Tatemoto, K.; Ono, Y.; Suzuki, R. O.

    2005-02-01

    For better oxidation resistance of refractory metals in air, the electroless coating of silicide in the molten salt was developed in open air at 973 1173 K. The molten salt consists of NaCl, KCl, Na2SiF6 and Si powder, where the proportional reaction between Si and Si4+ ions forms Si2+ ions. Si2+ deposits on the metal substrate and forms the metal silicide. The deposited silicide layers were classified into two categories depending on the metal substrates: (1) Nb, Mo and Cr mainly formed silicon-rich disilicide (MSi2) layer. (2) Fe, Ni and Co formed silicon-poor silicide layer (MSin, n<2), such as Fe3Si. This difference was described by the diffusivity of Si through the silicide layer into the metal.

  7. Metal Contacts on Semiconducting Two-Dimension Crystals

    NASA Astrophysics Data System (ADS)

    Liu, Han; Neal, Adam; Du, Yuchen; Ye, Peide

    2013-03-01

    Semiconducting 2-D crystals, such as MoS2, WSe2, are viewed as promising candidates for electronic applications for their high carrier mobility, thermal stability, compatibility to CMOS process, and superior immunity to short channel effects. However, with the difficulty in ion implantation, the metal contacts on 2-D crystals are yet with large contact resistance, thus eliminates further device performance. We study different metal contacts from low work function to high work function metals on MoS2 and WSe2 crystals with various thicknesses and discuss the Fermi level pinning at the metal/semiconductor interface. Effective Schottky Barrier Heights (SBHs) are also measured. Molecular doping and dual-side contacts metals are performed as two tentative solutions to reduce the effective SBHs, and high-performance of field effect transistors are achieved by reduced contact resistance.

  8. Observations on the measurement of total antimony and antimony species in algae, plant and animal tissues.

    PubMed

    Foster, S; Maher, W; Krikowa, F; Telford, K; Ellwood, M

    2005-12-01

    This paper describes our experiences with undertaking measurements of total antimony and antimony speciation in algae, plant and animal tissues. Digestion with nitric acid alone is suitable to release antimony from animal tissues. When organisms have high silica contents, e.g. some plants and algae, the addition of tetrafluorboric acid is required to dissolve silica as some antimony is retained by silica in extracts. Antimony in digested extracts is present as Sb5+ and hydride generation procedures can be used to determine total antimony concentrations, as total antimony in extracts will not be under estimated. Relatively non-aggressive solvents such as water, dilute nitric acid, sodium hydroxide and enzymes remove highly variable amounts of antimony (2-84%) from algae, plant and animal tissues. Addition of Sb3+ and Sb5+ to NIST CRM 1572 Citrus Leaves, pre- and post-extraction with water showed that Sb3+ is oxidised to Sb5+ while Sb5+ is redistributed amongst binding sites giving rise to artefacts. DOLT-2 and algae extracts indicated the presence of only inorganic antimony. A moss sample had inorganic antimony and a number of unknown antimony species in extracts. Future studies should explore the nature of the binding of antimony in tissues as solvents commonly used to extract metals and metalloids from algae, plant and animal tissues are not appropriate. PMID:16307074

  9. Metal Load of the Crops Depending on Land Use, Land Management and Soil Characteristics

    NASA Astrophysics Data System (ADS)

    Oeztan, Sezin; Duering, Rolf-Alexander

    2010-05-01

    The increase of pollutant concentrations in soil and in the food chain became very important in the past few decades. Metals of different toxicities (Cd, Zn, As, Cr, Cu, Pb, Ni, Co, V, Tl) occur in soils as a result of weathering, industrial processes, fertilization and atmospheric deposition. Some of them can be absorbed by the plants due to their mobility. The transfer of metals from soil into the plants can be explained by the physicochemical characteristics of the soil such as pH-value, organic matter and clay content. Badly adapted cultivation of the agricultural soils (declining pH-value, application of unsuitable fertilizers) can enhance the mobility of the metals and by the way increase their concentrations in agricultural products. With this study, a field experiment was established and the aim is to test the relations between available metal concentrations in the soil and metal load of the plants depending on the fertilization techniques. The plants and soil samples of the reference sites were taken, heavy metal contents of the soil samples identified by Microwave Assisted Extraction (MAE) and compared to the Aqua Regia Digestion Method for confirming the methodology. For the determination of the metal content in plants, MAE was executed to the selected plant samples and for that procedure, the samples were digested with HNO3 and H2O2 in the microwave oven. Quantation of the metals in soil and in plants was done by ICP-OES Methodology. The evaluation of the first results confirmed that the metal content of the soil is strongly dependent on the properties of different fertilization variants (N,P,K) used and physicochemical characteristics of the soils. According to the fertilization variants, total metal contents of the soil are increased in the soil samples which have high amounts of N, P, K fertilization. Soils which were enforced with high P fertilization degrees had significantly higher total Cd content. Results on the Cd content of the plant samples

  10. Electrochemical instrumentation of a hip simulator: a new tool for assessing the role of corrosion in metal-on-metal hip joints.

    PubMed

    Yan, Y; Neville, A; Dowson, D; Williams, S; Fisher, J

    2010-11-01

    Polyethylene wear debris induced osteolysis has triggered investigations to find alternative material combinations to the well-established metal-on-polyethylene hip implants. Owing to some early successful clinical cases, metal-on-metal (MoM) hip replacements have been attracting more and more interest. There is, however, considerable concern about the propensity of MoM hip replacements to release metal ions and fine, nanometre-scale metallic wear debris. The long-term effect from released metal ions and wear particles is still not clear. To date, all the work on hip simulators focused on assessing mass losses damage has been referred to as 'wear'. However, it is known in the field of tribocorrosion that mechanical removal of the passive layer on Co-Cr alloys can significantly enhance corrosion activity. In total joint replacements, it is possible that corrosion plays a significant role. However, no one has ever tried to extract, on a hip simulator, what proportion of the damage is due to mechanical processes and the corrosion processes. This paper describes the first instrumentation of an integrated hip joint simulator to provide in-situ electrochemical measurements in real time. The open circuit potential results are reported to assess the corrosion regime in the absence and presence of movement at the bearing surfaces. The importance of these measurements is that the real damage mechanisms can be assessed as a function of the operating cycle. PMID:21218689

  11. Metallic particle sizing on flat surfaces: Application to conducting substrates

    NASA Astrophysics Data System (ADS)

    Moreno, F.; Saiz, J. M.; Valle, P. J.; González, F.

    1996-05-01

    A fast and accurate microsizing method is introduced and analyzed for metallic protuberances on flat substrates. It is based on the measurement of the minima angular positions of the S-polarized far field scattering patterns at normal incidence. The proposed method has been theoretically and experimentally checked for both cylindrical and spherical metallic protuberances on conducting flat substrates. The excellent agreement between theory and experiment proves the efficiency of the method. We also comment on the application of this method for other protuberance geometries and different substrates other than metallic.

  12. Influence of strain and metal thickness on metal-MoS{sub 2} contacts

    SciTech Connect

    Saidi, Wissam A.

    2014-09-07

    MoS{sub 2} and other transition metal dichalcogenides are considered as potential materials in many applications including future electronics. A prerequisite for these applications is to understand the nature of the MoS{sub 2} contact with different metals. We use semi-local density functional theory in conjunction with dispersion corrections to study the heterostructures composed of Pd and Pt monolayers with (111) orientation grown pseudomorphically on MoS{sub 2}(001). The interface properties are mapped as a function of the number of deposited overlayers, as well as a function of tensile and compressive strains. Although we show that the dependence of the contacts on strain can be fully explained using the d-band model, we find that their evolution with the number of deposited metal layers is markedly different between Pd and Pt, and at variance with the d-band model. Specifically, the Pt/MoS{sub 2} heterostructures show an anomalous large stability with the deposition of two metal monolayers for all investigated strains, while Pd/MoS{sub 2} exhibits a similar behavior only for compressive strains. It is shown that the results can be rationalized by accounting for second-nearest-neighbor effect that couples MoS{sub 2} with the subsurface metal layers. The underpinnings of this behavior are attributed to the larger polarizability and cohesive energy of Pt compared to Pd, that leads to a larger charge-response in the subsurface layers.

  13. Effect of Hydrogen on Interfacial Structure and Adhesion of Metal/Al_2O_3

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Gang; Scheffler, Matthias

    2001-03-01

    Metal/sapphire interfaces have been intensively studying because of their importance in many technological applications. A large work of adhesion was found for the oxygen-terminated Al_2O_3(0001)/metal interfaces. As well known, the clean oxygen-terminated Al_2O3 surface is not stable even under a high oxygen pressure[1]. The understanding of how the oxygen-terminated interfaces can be formed is limited. Using an ab initio full-potential linearized augmented plane wave method, we investigated the effect of hydrogen on the formation of metal/Al_2O_3(0001) interfaces. Our results reveal that hydrogen plays an important role in the formation of the oxygen-terminated interfaces. Hydrogen impurities greatly decrease the work of adhesion. The behavior of hydrogen in deposition process of ultrathin metal films on sapphire substrates and the possible structures of the ultrathin films are discussed also. [1] Xiao-Gang Wang, Anne Chaka, Matthias Scheffler, Phys. Rev. Lett. 84, 3650 (2000).

  14. Metal on metal surface replacement of the hip. Experience of the McMinn prothesis.

    PubMed

    McMinn, D; Treacy, R; Lin, K; Pynsent, P

    1996-08-01

    The historical failure of surface replacement has been due to the production of wear debris with subsequent bone resorption, loosening, and failure. To avoid these problems, a surface replacement using a metal on metal bearing allowing thin components and femoral design and instrumentation to avoid varus alignment has been designed. Two hundred thirty-five joints have been resurfaced with this prosthesis in almost 5 years. There have been no femoral neck fractures and no dislocations. There have been 4 designs differing in the method of fixation. In the press fit group, 6 of 70 hips had to be revised for aseptic loosening. In the cemented group, debonding of the cup occurred in 3 of 43 cases. Six patients had hydroxyapatite coated components and have had excellent clinical outcomes. The current design uses a peripherally expanded hydroxyapatite coated cup and a cemented metal head; 116 of this design have been implanted during a 19-month period with excellent outcome. Despite short followup the authors are hopeful that the combination of a polar metal on metal bearing with appropriate fixation will yield a method of preserving bone stock in the younger patient requiring arthroplasty. PMID:8769326

  15. Nondestructive method for reconnecting aluminum metallization on integrated circuits.

    PubMed

    Zubatkin, A D

    1979-07-01

    A failure analysis technique for reconnecting aluminum metallization on planar IC devices is described. The technique, utilizing a conductive paint deposited on the device surface, is nondestructive and easily removable. PMID:18699636

  16. Evaluation of sample preparation methods for the detection of total metal content using inductively coupled plasma optical emission spectrometry (ICP-OES) in wastewater and sludge

    NASA Astrophysics Data System (ADS)

    Dimpe, K. M.; Ngila, J. C.; Mabuba, N.; Nomngongo, P. N.

    Heavy metal contamination exists in aqueous wastes and sludge of many industrial discharges and domestic wastewater, among other sources. Determination of metals in the wastewater and sludge requires sample pre-treatment prior to analysis because of certain challenges such as the complexity of the physical state of the sample, which may lead to wrong readings in the measurement. This is particularly the case with low analyte concentration to be detected by the instrument. The purpose of this work was to assess and validate the different sample preparation methods namely, hot plate and microwave-assisted digestion procedures for extraction of metal ions in wastewater and sludge samples prior to their inductively coupled plasma optical emission spectrometric (ICP-OES) determination. For the extraction of As, Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn, three acid mixtures, that is, HNO3/H2O2, HNO3/HClO4/H2O2 and aqua regia + H2O2, were evaluated. Influent wastewater spiked with the SRM (CWW-TM-B) was used for the optimization of acid mixtures affecting the extraction procedure. After sample digestion, the filtration capabilities of cellulose-acetate filter paper and the acrodisc syringe filter with the pore size of 0.45 μm were compared. In terms of performance, acrodisc syringe filter in terms of the improved recoveries obtained, was found to be the best filtration method compared to the filter paper. Based on the analytical results obtained, microwave-assisted digestion (MAD) using aqua regia + H2O2 mixture was found to be the most suitable method for extraction of heavy metals and major elements in all the sample matrices. Therefore, MAD using aqua regia + H2O2 mixture was used for further investigations. The precision of the developed MAD method expressed in terms of relative standard deviations (% RSD) for different metals was found to be <5%. The limits of detection (LOD) and limits of quantification (LOQ) ranged from 0.12% to 2.18 μg L-1 and 0.61% to 3.43 μg L-1

  17. Flexible metal-insulator-metal capacitors on polyethylene terephthalate plastic substrates

    NASA Astrophysics Data System (ADS)

    Hota, M. K.; Bera, M. K.; Maiti, C. K.

    2012-10-01

    Realization of flexible electronic devices on polyethylene terephthalate flexible plastic substrates is reported. Metal-insulator-metal capacitors have been fabricated using radio frequency sputtered deposited thin films of Nb2O5 on the flexible substrate. Good electrical characteristics have been obtained in terms of quadratic voltage coefficient of capacitance, high capacitance density (˜ 11 fF µm-2), high dielectric constant (˜37) and low dissipation factor (<0.1). Besides, in repetitive bending test, the devices show excellent electrical stability and high mechanical flexibility due to the high ductility of niobium and low-temperature processing used in this study.

  18. Influence of introduced Sonneratia apetala on nutrients and heavy metals in intertidal sediments

    NASA Astrophysics Data System (ADS)

    Li, ruili; chai, minwei; Qiu, guo yu

    2015-04-01

    To investigate the influence of Sonneratia apetala on nutrients and heavy metals in intertidal sediments, core sediments from a S. apetala forest and adjacent mud flat in Futian Nature Reserve (Shenzhen Bay, China) were analyzed. The results showed that total carbon (TC), total nitrogen (TN), and total sulfur (TS) in S. apetala site were higher than mud flat site, indicating its improvement on soil nutrient properties. Concentrations of As (S. apetala: 199.66 μg/g, mud flat: 152.40 μg/g) were higher than probable effect concentrations, suggesting heavy pollution of As in sediments of S. apetala and mud flat sites. Furthermore, compared with mud flat site, sediments from S. apetala site have higher heavy metals, including Cr, Ni, Cu, Zn, As, Cd, Pb, and Hg. Overall, the heavy metals in both sites were in the same order of Zn > As > Hg > Cr > Cu ˜ Pb > Ni > Cd. In S. apetala site, organic matters (TC, TN, and TS) were positively correlated with Cu, Zn, and Hg, different from Cu, Zn, Hg, and Cd in mud flat site, indicating less important role of organic matter in trapping heavy metals. In addition, there were positive correlations among Ni, Cu, Zn, and Cd in S. apetala and mud flat sites, indicating the similar sources mainly from increasing municipal and industrial wastewater discharges.

  19. Role of metal nanoparticles on porosification of silicon by metal induced etching (MIE)

    NASA Astrophysics Data System (ADS)

    Saxena, Shailendra K.; Yogi, Priyanka; Yadav, Pooja; Mishra, Suryakant; Pandey, Haardik; Rai, Hari Mohan; Kumar, Vivek; Sagdeo, Pankaj R.; Kumar, Rajesh

    2016-06-01

    Porosification of silicon (Si) by metal induced etching (MIE) process has been studied here to understand the etching mechanism. The etching mechanism has been discussed on the basis of electron transfer from Si to metal ion (Ag+) and metal to H2O2. Role of silver nanoparticles (AgNPs) in the etching process has been investigated by studying the effect of AgNPs coverage on surface porosity. A quantitative analysis of SEM images, done using Image J, shows a direct correlation between AgNPs coverage and surface porosity after the porosification. Density of Si nanowires (NWs) also varies as a function of AgNPs fractional coverage which reasserts the fact that AgNPs governs the porosification process during MIE. The Raman and PL spectrum show the presence of Si NSs in the samples.

  20. [Radiance Simulation of BUV Hyperspectral Sensor on Multi Angle Observation, and Improvement to Initial Total Ozone Estimating Model of TOMS V8 Total Ozone Algorithm].

    PubMed

    Lü, Chun-guang; Wang, Wei-he; Yang, Wen-bo; Tian, Qing-iju; Lu, Shan; Chen, Yun

    2015-11-01

    New hyperspectral sensor to detect total ozone is considered to be carried on geostationary orbit platform in the future, because local troposphere ozone pollution and diurnal variation of ozone receive more and more attention. Sensors carried on geostationary satellites frequently obtain images on the condition of larger observation angles so that it has higher requirements of total ozone retrieval on these observation geometries. TOMS V8 algorithm is developing and widely used in low orbit ozone detecting sensors, but it still lack of accuracy on big observation geometry, therefore, how to improve the accuracy of total ozone retrieval is still an urgent problem that demands immediate solution. Using moderate resolution atmospheric transmission, MODT-RAN, synthetic UV backscatter radiance in the spectra region from 305 to 360 nm is simulated, which refers to clear sky, multi angles (12 solar zenith angles and view zenith angles) and 26 standard profiles, moreover, the correlation and trends between atmospheric total ozone and backward scattering of the earth UV radiation are analyzed based on the result data. According to these result data, a new modified initial total ozone estimation model in TOMS V8 algorithm is considered to be constructed in order to improve the initial total ozone estimating accuracy on big observation geometries. The analysis results about total ozone and simulated UV backscatter radiance shows: Radiance in 317.5 nm (R₃₁₇.₅) decreased as the total ozone rise. Under the small solar zenith Angle (SZA) and the same total ozone, R₃₁₇.₅ decreased with the increase of view zenith Angle (VZA) but increased on the large SZA. Comparison of two fit models shows: without the condition that both SZA and VZA are large (> 80°), exponential fitting model and logarithm fitting model all show high fitting precision (R² > 0.90), and precision of the two decreased as the SZA and VZA rise. In most cases, the precision of logarithm fitting

  1. Metal-and hydrogen-bonding competition during water absorption on Pd(111) and Ru(0001)

    SciTech Connect

    Tatarkhanov, Mouslim; Ogletree, D. Frank; Rose, Franck; Mitsui, Toshiyuki; Fomin, Evgeny; Rose, Mark; Cerda, Jorge I.; Salmeron, Miquel

    2009-09-03

    The initial stages of water adsorption on the Pd(111) and Ru(0001) surfaces have been investigated experimentally by Scanning Tunneling Microscopy in the temperature range between 40 K and 130 K, and theoretically with Density Functional Theory (DFT) total energy calculations and STM image simulations. Below 125 K water dissociation does not occur at any appreciable rate and only molecular films are formed. Film growth starts by the formation of flat hexamer clusters where the molecules bind to the metal substrate through the O-lone pair while making H-bonds with neighboring molecules. As coverage increases, larger networks of linked hexagons are formed with a honeycomb structure, which requires a fraction of the water molecules to have their molecular plane perpendicular to the metal surface with reduced water-metal interaction. Energy minimization favors the growth of networks with limited width. As additional water molecules adsorb on the surface they attach to the periphery of existing islands, where they interact only weakly with the metal substrate. These molecules hop along the periphery of the clusters at intermediate temperatures. At higher temperatures they bind to the metal to continue the honeycomb growth. The water-Ru interaction is significantly stronger than the water-Pd interaction, which is consistent with the greater degree of hydrogen-bonded network formation and reduced water-metal bonding observed on Pd relative to Ru.

  2. Metal-carbon nanocomposites based on activated IR pyrolized polyacrylonitrile

    NASA Astrophysics Data System (ADS)

    Efimov, Mikhail N.; Zhilyaeva, Natalya A.; Vasilyev, Andrey A.; Muratov, Dmitriy G.; Zemtsov, Lev M.; Karpacheva, Galina P.

    2016-05-01

    In this paper we report about new approach to preparation of metal-carbon nanocomposites based on activated carbon. Polyacrylonitrile is suggested as a precursor for Co, Pd and Ru nanoparticles carbon support which is prepared under IR pyrolysis conditions of a precursor. The first part of the paper is devoted to study activated carbon structural characteristics dependence on activation conditions. In the second part the effect of type of metal introduced in precursor on metal-carbon nanocomposite structural characteristics is shown. Prepared AC and nanocomposite samples are characterized by BET, TEM, SEM and X-ray diffraction.

  3. Evaluation of metal texture effect on paint appearance

    NASA Astrophysics Data System (ADS)

    Kang, Haizhuang; Butler, Clive; Yang, Qingping

    1999-11-01

    With the increasing improvement on painting techniques in automotive industry, high quality paint appearance with high gloss, clear image and low orange peel can be achieved on car bodies. In this case, another defect called `metal texture effect' is becoming more significant to paint appearance. In this paper, image texture analysis method, gray-tone spatial-dependence matrices have been employed to evaluate metal texture effect on paint appearance. The preliminary experimental result showed that this method could effectively evaluated metal texture effect as perceived with human eye.

  4. Total Variance: A Progress Report on a New Frequency Stability Characterization

    NASA Technical Reports Server (NTRS)

    Howe, D. A.; Greenhall, C. A.

    1997-01-01

    We give results of recent work on a newly developed frequency stability characterization, called Total variance, whose main advantages are improved confidence at and near the longest averaging time of half the data duration, and lower sensitivity to drift removal.

  5. Metal Ion Sensors Based on DNAzymes and Related DNA Molecules

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao-Bing; Kong, Rong-Mei; Lu, Yi

    2011-07-01

    Metal ion sensors are an important yet challenging field in analytical chemistry. Despite much effort, only a limited number of metal ion sensors are available for practical use because sensor design is often a trial-and-error-dependent process. DNAzyme-based sensors, in contrast, can be developed through a systematic selection that is generalizable for a wide range of metal ions. Here, we summarize recent progress in the design of DNAzyme-based fluorescent, colorimetric, and electrochemical sensors for metal ions, such as Pb2+, Cu2+, Hg2+, and UO22+. In addition, we also describe metal ion sensors based on related DNA molecules, including T-T or C-C mismatches and G-quadruplexes.

  6. Process for making a noble metal on tin oxide catalyst

    NASA Technical Reports Server (NTRS)

    Upchurch, Billy T. (Inventor); Davis, Patricia (Inventor); Miller, Irvin M. (Inventor)

    1989-01-01

    A quantity of reagent grade tin metal or compound, chloride-free, and high-surface-area silica spheres are placed in deionized water, followed by deaerating the mixture by boiling and adding an oxidizing agent, such as nitric acid. The nitric acid oxidizes the tin to metastannic acid which coats the spheres because the acid is absorbed on the substrate. The metastannic acid becomes tin oxide upon drying and calcining. The tin-oxide coated silica spheres are then placed in water and boiled. A chloride-free precious metal compound in aqueous solution is then added to the mixture containing the spheres, and the precious metal compound is reduced to a precious metal by use of a suitable reducing agent such as formic acid. Very beneficial results were obtained using the precious metal compound tetraammine platinum(II) hydroxide.

  7. Metal Ion Sensors Based on DNAzymes and Related DNA Molecules

    PubMed Central

    Kong, Rong-Mei

    2011-01-01

    Metal ion sensors are an important yet challenging field in analytical chemistry. Despite much effort, only a limited number of metal ion sensors are available for practical use because sensor design is often a trial-and-error-dependent process. DNAzyme-based sensors, in contrast, can be developed through a systematic selection that is generalizable for a wide range of metal ions. Here, we summarize recent progress in the design of DNAzyme-based fluorescent, colorimetric, and electrochemical sensors for metal ions, such as Pb2+, Cu2+, Hg2+, and UO22+ In addition, we also describe metal ion sensors based on related DNA molecules, including T-T or C-C mismatches and G-quadruplexes. PMID:21370984

  8. Clinical Usefulness of SPECT-CT in Patients with an Unexplained Pain in Metal on Metal (MOM) Total Hip Arthroplasty.

    PubMed

    Berber, Reshid; Henckel, Johann; Khoo, Michael; Wan, Simon; Hua, Jia; Skinner, John; Hart, Alister

    2015-04-01

    SPECT-CT is increasingly used to assess painful knee arthroplasties. The aim of this study was to evaluate the clinical usefulness of SPECT-CT in unexplained painful MOM hip arthroplasty. We compared the diagnosis and management plan for 19 prosthetic MOM hips in 15 subjects with unexplained pain before and after SPECT-CT. SPECT-CT changed the management decision in 13 (68%) subjects, Chi-Square=5.49, P=0.24. In 6 subjects (32%) pain remained unexplained however the result reassured the surgeon to continue with non-operative management. SPECT-CT should be reserved as a specialist test to help identify possible causes of pain where conventional investigations have failed. It can help reassure surgeons making management decisions for patients with unexplained pain following MOM hip arthroplasty. PMID:25583682

  9. Metal-phthalocyanine ordered layers on Au(110): Metal-dependent adsorption energy

    SciTech Connect

    Massimi, Lorenzo Angelucci, Marco; Gargiani, Pierluigi; Betti, Maria Grazia; Montoro, Silvia; Mariani, Carlo

    2014-06-28

    Iron-phthalocyanine and cobalt-phthalocyanine chains, assembled along the Au(110)-(1×2) reconstructed channels, present a strong interaction with the Au metallic states, via the central metal ion. X-ray photoemission spectroscopy from the metal-2p core-levels and valence band high-resolution ultraviolet photoelectron spectroscopy bring to light signatures of the interaction of the metal-phthalocyanine single-layer with gold. The charge transfer from Au to the molecule causes the emerging of a metal-2p core level component at lower binding energy with respect to that measured in the molecular thin films, while the core-levels associated to the organic macrocycle (C and N 1s) are less influenced by the adsorption, and the macrocycles stabilize the interaction, inducing a strong interface dipole. Temperature Programmed Desorption experiments and photoemission as a function of temperature allow to estimate the adsorption energy for the thin-films, mainly due to the molecule-molecule van der Waals interaction, while the FePc and CoPc single-layers remain adsorbed on the Au surface up to at least 820 K.

  10. Total internal reflection mirror-based ultra-sensitive triangular ring resonator sensor on the surface plasmon resonance condition

    NASA Astrophysics Data System (ADS)

    Kim, Hong-Seung; Kim, Tae-Ryong; Kim, Doo-Gun; Choi, Young-Wan

    2015-02-01

    In this paper, we have theoretically analyzed using a finite-difference time domain (FDTD) methods and realized a high sensitive triangular ring resonator sensor based on the total internal reflection (TIR) mirror with a thin metal film for surface plasmon resonance (SPR) phenomenon. One of advantages is a high sensitivity with large phase variation at TIR mirror facet with SPR. Previously, the sensing region of the general ring resonator sensor is located on the cladding region or upper core region. However, the triangular ring resonator has a very high sensitivity using the sensing region of the TIR mirror facet, because the length of the evanescent field at TIR mirror is longer than the evanescent field length at the cladding region. Another is a high Q-factor by the round-trip loss compensation through an active medium in the waveguide. Proposed sensor also has an integrated light source using an InP-based semiconductor optical amplifier. The sensitivity of triangular ring resonator with SPR is extremely enhanced by large phase shift at TIR mirror facet on SPR. Optimized metal thickness is a 33.4 nm at the SPR angle of 22.92 degree. The simulation result of the sensitivity for the triangular ring resonator sensor with SPR is 4.2×104 nm/RIU using by FDTD method. To measure the biosensor, we used an antigen/antibody reaction.

  11. Contact resistance in metal-molecule-metal junctions based on aliphatic SAMs: effects of surface linker and metal work function.

    PubMed

    Beebe, Jeremy M; Engelkes, Vincent B; Miller, Larry L; Frisbie, C Daniel

    2002-09-25

    Using conducting probe atomic force microscopy (CP-AFM), we have formed molecular tunnel junctions consisting of alkanethiols and alkane isonitrile self-assembled monolayers sandwiched between gold, platinum, silver, and palladium contacts. We have measured the resistance of these junctions at low bias (dV/dI |V=0) as a function of alkane chain length. Extrapolation to zero chain length gives the contact resistance, R0 . R0 is strongly dependent on the type of metal used for the contacts and decreases with increasing metal work function; that is, R0,Ag > R0,Au > R0,Pd > R0,Pt. R0 is approximately 10% smaller for Au junctions with isonitrile versus thiol surface linkers. We conclude that the Fermi level of the junction lies much closer to the HOMO than to the LUMO. PMID:12236731

  12. The effects of fluid turbulence on metal vapor nucleation

    NASA Astrophysics Data System (ADS)

    Liu, Jun; Garrick, Sean

    2010-11-01

    The rising need for clean, renewable energy sources has led to recent studies on hydrogen production via hydrolysis of zinc nanoparticles. Aerosol or gas-phase processes are favored in many industrial applications due to its advantage in controlling particle size distribution and the resultant chemical conversion. The rising need for clean, renewable energy sources has led to recent studies on hydrogen production via hydrolysis of zinc nanoparticles. Aerosol or gas-phase processes are favored in many industrial applications due to its advantage in controlling particle size distribution and the resultant chemical conversion. In this work we study the formation of metal particles in a shear flows. Direct numerical simulation of homogeneous metal vapor nucleation in laminar and turbulent flows are performed for a variety of metals. The flows consist of hot metal vapor issuing into cooler inert gas. As the metal vapor cools, nanoparticles form and are transported throughout the flow-field. Homogeneous nucleation is simulated using classical nucleation theory and two approaches to representing the surface tension. The effects of three-dimensional turbulent mixing are also analyzed. The results suggest that fluid, thermal and species mixing greatly affects the nucleation dynamics. We report on the effects of vapor concentration level, fluid mixing, and particle surface tension on the conversion from metal vapor to metal nanoparticles.

  13. Controls on metal exposure to aquatic organisms in urban streams.

    PubMed

    Turpin-Nagel, Katelyn; Vadas, Timothy M

    2016-08-10

    Streams in urban ecosystems receive metal inputs primarily from stormwater runoff and wastewater effluent. The relative contribution of these metal sources to stream impairment is difficult to discern based on simple water characteristics and biological surveys. Stream impairment in these systems is often indicated by reduced abundance and diversity of aquatic insects, which tend to be more sensitive to chronic metal exposures. Metal species and controls on metal species in both the waterborne and dietborne exposure pathways to aquatic organisms are reviewed here. In addition, ecological changes that can control dietborne species are discussed. A main focus is on how organic matter from different anthropogenic sources may control both aqueous metal speciation as well as interaction with various inorganic or microbiological surfaces in streams. Most of the reviewed research focuses on Cu, Zn or Pb as those are the primary metals of concern in developed systems and Cu and Pb have unique and strong interactions with organic matter. Recommendations for further research are described in the context of exposure species, dynamics of exposure, stoichiometry, or advanced analytical tools, and regulatory implications are discussed. PMID:27170052

  14. Impact of metal pollution on fungal diversity and community structures.

    PubMed

    Op De Beeck, Michiel; Lievens, Bart; Busschaert, Pieter; Rineau, Francois; Smits, Mark; Vangronsveld, Jaco; Colpaert, Jan V

    2015-06-01

    The impact of metal pollution on plant communities has been studied extensively in the past, but little is known about the effects of metal pollution on fungal communities that occur in metal-polluted soils. Metal-tolerant ecotypes of the ectomycorrhizal fungus Suillus luteus are frequently found in pioneer pine forests in the Campine region in Belgium on metal-polluted soils. We hypothesized that metal pollution would play an important role in shaping below-ground fungal communities that occur in these soils and that Suillus luteus would be a dominant player. To test these hypotheses, the fungal communities in a young pine plantation in soil polluted with zinc, and cadmium were studied using 454 amplicon pyrosequencing. Results show that zinc, cadmium and soil organic matter content were strongly correlated with the fungal community composition, but no effects on fungal diversity were observed. As hypothesized, S. luteus was found to be a dominant member of the studied fungal communities. However, other dominant fungal species, such as Sistotrema sp., Wilcoxina mikolae and Cadophora finlandica were found as well. Their presence in metal-polluted sites is discussed. PMID:24947496

  15. Quantum Chemical Study of Raman Spectroscopy of Substituted Benzene Derivatives Adsorbed on Metal Surfaces

    NASA Astrophysics Data System (ADS)

    Wu, De-Yin; Tian, Zhong-Qun

    2011-06-01

    Surface-enhanced Raman spectroscopy (SERS) can be applied to obtain the information of molecules at the noble metal surfaces. But there are a number of difficulties to clearly correlate Raman spectra with microscopic molecular structures on metal surfaces. The main reason is that it is difficult to characterize unambiguously the metal surface structures and the influence of the binding interaction on SERS signals of the probe molecules. According to the surface selection rule of SERS, the electromagnetic enhancement will not change relative Raman intensities of vibrational modes with the same irreducible representation. Therefore, the change of the relative Raman intensities of the total symmetric modes may only originate from the chemical enhancement. In order to understand how the chemical interaction modulates the Raman intensity of individual modes, it is necessary to systematically investigate the Raman spectra of probe molecules themselves and the dependence of SERS signals on the binding interaction, adsorption sites, excitation wavelengths and metal property. Some probe molecules, including aniline, 1,4-benzenediamine, p-aminothiophenol, benzyl chlorine, and 4,4^'-bipyridine are investigated based on quantum chemical calculations. Raman spectra of these molecules and their adsorbed species were predicted and compared with experimentally measured spectra. The metal surfaces were mimicked using the metallic cluster model, where the silver or gold surfaces were replaced by silver or gold clusters, respectively. The density functional theory approach was employed to obtain the optimized structures and vibrational spectra by combining all-electron basis sets of 6-311+G** for atoms in the molecules and the poseudopotential basis set of LANL2DZ for metal atoms. The vibrational frequency shift and the relative Raman intensity are related to the adsorption configuration of the probe molecules. For all these molecules, the ring breathing mode and the C-C stretching

  16. Detuned Plasmonic Bragg Grating Sensor Based on a Defect Metal-Insulator-Metal Waveguide

    PubMed Central

    Qu, Shinian; Song, Ci; Xia, Xiushan; Liang, Xiuye; Tang, Baojie; Hu, Zheng-Da; Wang, Jicheng

    2016-01-01

    A nanoscale Bragg grating reflector based on the defect metal-insulator-metal (MIM) waveguide is developed and numerically simulated by using the finite element method (FEM). The MIM-based structure promises a highly tunable broad stop-band in transmission spectra. The narrow transmission window is shown to appear in the previous stop-band by changing the certain geometrical parameters. The central wavelengths can be controlled easily by altering the geographical parameters. The development of surface plasmon polarition (SPP) technology in metallic waveguide structures leads to more possibilities of controlling light at deep sub-wavelengths. Its attractive ability of breaking the diffraction limit contributes to the design of optical sensors. PMID:27240381

  17. Detuned Plasmonic Bragg Grating Sensor Based on a Defect Metal-Insulator-Metal Waveguide.

    PubMed

    Qu, Shinian; Song, Ci; Xia, Xiushan; Liang, Xiuye; Tang, Baojie; Hu, Zheng-Da; Wang, Jicheng

    2016-01-01

    A nanoscale Bragg grating reflector based on the defect metal-insulator-metal (MIM) waveguide is developed and numerically simulated by using the finite element method (FEM). The MIM-based structure promises a highly tunable broad stop-band in transmission spectra. The narrow transmission window is shown to appear in the previous stop-band by changing the certain geometrical parameters. The central wavelengths can be controlled easily by altering the geographical parameters. The development of surface plasmon polarition (SPP) technology in metallic waveguide structures leads to more possibilities of controlling light at deep sub-wavelengths. Its attractive ability of breaking the diffraction limit contributes to the design of optical sensors. PMID:27240381

  18. Green approach for ultratrace determination of divalent metal ions and arsenic species using total-reflection X-ray fluorescence spectrometry and mercapto-modified graphene oxide nanosheets as a novel adsorbent.

    PubMed

    Sitko, Rafal; Janik, Paulina; Zawisza, Beata; Talik, Ewa; Margui, Eva; Queralt, Ignasi

    2015-03-17

    A new method based on dispersive microsolid phase extraction (DMSPE) and total-reflection X-ray fluorescence spectrometry (TXRF) is proposed for multielemental ultratrace determination of heavy metal ions and arsenic species. In the developed methodology, the crucial issue is a novel adsorbent synthesized by grafting 3-mercaptopropyl trimethoxysilane on a graphene oxide (GO) surface. Mercapto-modified graphene oxide (GO-SH) can be applied in quantitative adsorption of cobalt, nickel, copper, cadmium, and lead ions. Moreover, GO-SH demonstrates selectivity toward arsenite in the presence of arsenate. Due to such features of GO-SH nanosheets as wrinkled structure and excellent dispersibility in water, GO-SH seems to be ideal for fast and simple preconcentration and determination of heavy metal ions using methodology based on DMSPE and TXRF measurement. The suspension of GO-SH was injected into an analyzed water sample; after filtration, the GO-SH nanosheets with adsorbed metal ions were redispersed in a small volume of internal standard solution and deposited onto a quartz reflector. The high enrichment factor of 150 allows obtaining detection limits of 0.11, 0.078, 0.079, 0.064, 0.054, and 0.083 ng mL(-1) for Co(II), Ni(II), Cu(II), As(III), Cd(II), and Pb(II), respectively. Such low detection limits can be obtained using a benchtop TXRF system without cooling media and gas consumption. The method is suitable for the analysis of water, including high salinity samples difficult to analyze using other spectroscopy techniques. Moreover, GO-SH can be applied to the arsenic speciation due to its selectivity toward arsenite. PMID:25707847

  19. Directional coupler and nonlinear Mach-Zehnder interferometer based on metal-insulator-metal plasmonic waveguide.

    PubMed

    Pu, Mingbo; Yao, Na; Hu, Chenggang; Xin, Xuecheng; Zhao, Zeyu; Wang, Changtao; Luo, Xiangang

    2010-09-27

    Directional coupler (DC) and nonlinear Mach-Zehnder interferometer (MZI) based on metal-insulator-metal (MIM) plasmonic waveguide are investigated numerically. We show that the coupling length increases almost linearly with the wavelength and this property is utilized in the design of wavelength division multiplexer (WDM). A nonlinear MZI, with one branch filled with Kerr nonlinear medium, is built to ensure controlling light with light. Employing nonlinear processes including self-phase modulation (SPM) and cross-phase modulation (XPM), intensity-based router and all-optical switch are realized. PMID:20940998

  20. Formation of carbyne and graphyne on transition metal surfaces

    NASA Astrophysics Data System (ADS)

    Yuan, Qinghong; Ding, Feng

    2014-10-01

    The electronic and geometric structures of carbyne on various transition metal surfaces were investigated by theoretical calculations. It was found that carbyne on non-active metal surfaces has a polyynic structure, while a polycumulenic structure is more stable on active catalyst surfaces. The self-assembly of carbyne on a metal substrate could lead to the synthesis of graphyne.The electronic and geometric structures of carbyne on various transition metal surfaces were investigated by theoretical calculations. It was found that carbyne on non-active metal surfaces has a polyynic structure, while a polycumulenic structure is more stable on active catalyst surfaces. The self-assembly of carbyne on a metal substrate could lead to the synthesis of graphyne. Electronic supplementary information (ESI) available: Computational details and structural information of carbon chains on Ni(111) and Rh(111) surfaces, carbon island on Cu(111), Ni(111), Rh(111) and Ru(0001) surfaces. See DOI: 10.1039/c4nr03757j

  1. The Effect of Porous Tantalum Cones on Mechanical Alignment and Canal-Fill Ratio in Revision Total Knee Arthroplasty Performed with Uncemented Stems.

    PubMed

    Bédard, Martin; Cabrejo-Jones, Katherine; Angers, Michèle; Pelletier-Roy, Rémi; Pelet, Stéphane

    2015-11-01

    In revision total knee arthroplasty (TKA), the internal diameter of metal cones may limit the ability of the stem to properly fill the medullary canal. We prospectively studied 115 patients who underwent revision TKA with uncemented stems to evaluate the effect of metal cones on mechanical alignment and stem positioning. Correction on the mechanical alignment was well achieved in all patients, regardless of whether a metal cone was used. The proportion of patients achieving restoration of neutral mechanical alignment was similar between groups, as were the mean canal fill ratio (CFR) and the proportion of patients achieving CFR ≥ 85%. The use of porous tantalum cones in revision TKA with uncemented stems is not an obstacle in achieving optimal mechanical alignment and stem positioning. PMID:26021903

  2. Effects of total dose irradiation on single-event upset hardness.

    SciTech Connect

    Paillet, Philippe; Ferlet-Cavrois, V.; Flores, Richard S.; Schwank, James Ralph; Felix, James Andrew; Shaneyfelt, Marty Ray; Hash, Gerald Leon; Cole, Edward Isaac, Jr.; Blackmore, E. W.; Dodd, Paul Emerson; Baggio, J.

    2005-04-01

    The effect of total dose on SEU hardness is investigated as a function of temperature and power supply voltage to determine worst case hardness assurance test conditions for space environments. SRAMs from six different vendors were characterized for single-event upset (SEU) hardness at proton energies from 20 to 500 MeV and at temperatures of 25 and 80 C after total dose irradiating the SRAMs with either protons, Co-60 gamma rays, or low-energy x-rays. It is shown that total dose irradiation and the bias configuration during total dose irradiation and SEU characterization can substantially affect SEU hardness for some SRAMs. For one SRAM, the bias configuration made more than two orders of magnitude difference in SEU cross section at the highest total dose level examined. In addition, it is shown that increasing the temperature during SEU characterization can also increase the effect of total dose on SEU hardness. As a result, worst-case SEU hardness assurance test conditions are the maximum total dose and temperature of the system environment, and the minimum operating voltage of the SRAM. In contrast to previous works, our results using selective area x-ray irradiations show that the source of the effect of total dose on SEU hardness is radiation-induced leakage currents in the memory cells. The increase in SEU cross section with total dose appears to be consistent with radiation-induced currents originating in the memory cells affecting the output bias levels of bias level shift circuitry used to control the voltage levels to the memory cells and/or due to the lowering of the noise margin of individual memory cells caused by radiation-induced leakage currents.

  3. The effects of soil amendments on heavy metal bioavailability in two contaminated Mediterranean soils.

    PubMed

    Walker, David J; Clemente, Rafael; Roig, Asuncion; Bernal, M Pilar

    2003-01-01

    Two heavy metal contaminated calcareous soils from the Mediterranean region of Spain were studied. One soil, from the province of Murcia, was characterised by very high total levels of Pb (1572 mg kg(-1)) and Zn (2602 mg kg(-1)), whilst the second, from Valencia, had elevated concentrations of Cu (72 mg kg(-1)) and Pb (190 mg kg(-1)). The effects of two contrasting organic amendments (fresh manure and mature compost) and the chelate ethylenediaminetetraacetic acid (EDTA) on soil fractionation of Cu, Fe, Mn, Pb and Zn, their uptake by plants and plant growth were determined. For Murcia soil, Brassica juncea (L.) Czern. was grown first, followed by radish (Raphanus sativus L.). For Valencia soil, Beta maritima L. was followed by radish. Bioavailability of metals was expressed in terms of concentrations extractable with 0.1 M CaCl2 or diethylenetriaminepentaacetic acid (DTPA). In the Murcia soil, heavy metal bioavailability was decreased more greatly by manure than by the highly-humified compost. EDTA (2 mmol kg(-1) soil) had only a limited effect on metal uptake by plants. The metal-solubilising effect of EDTA was shorter-lived in the less contaminated, more highly calcareous Valencia soil. When correlation coefficients were calculated for plant tissue and bioavailable metals, the clearest relationships were for Beta maritima and radish. PMID:12531318

  4. Are all metal-on-metal hip revision operations contributing to the National Joint Registry implant survival curves?

    PubMed Central

    Sabah, S. A.; Henckel, J.; Koutsouris, S.; Rajani, R.; Hothi, H.; Skinner, J. A.; Hart, A. J.

    2016-01-01

    Aims The National Joint Registry for England, Wales and Northern Ireland (NJR) has extended its scope to report on hospital, surgeon and implant performance. Data linkage of the NJR to the London Implant Retrieval Centre (LIRC) has previously evaluated data quality for hip primary procedures, but did not assess revision records. Methods We analysed metal-on-metal hip revision procedures performed between 2003 and 2013. A total of 69 929 revision procedures from the NJR and 929 revised pairs of components from the LIRC were included. Results We were able to link 716 (77.1%) revision procedures on the NJR to the LIRC. This meant that 213 (22.9%) revision procedures at the LIRC could not be identified on the NJR. We found that 349 (37.6%) explants at the LIRC completed the full linkage process to both NJR primary and revision databases. Data completion was excellent (> 99.9%) for revision procedures reported to the NJR. Discussion This study has shown that only approximately one third of retrieved components at the LIRC, contributed to survival curves on the NJR. We recommend prospective registry-retrieval linkage as a tool to feedback missing and erroneous data to the NJR and improve data quality. Take home message: Prospective Registry – retrieval linkage is a simple tool to evaluate and improve data quality on the NJR. Cite this article: Bone Joint J 2016;98-B:33–9. PMID:26733513

  5. [Advance of studies on bioactivity of flavonoid-metal complexes].

    PubMed

    Liu, Yanji; He, Xiaoyan; Zuo, Hua; Zhang, Qixiong; Li, Zhubo; Shi, Lunyong

    2012-07-01

    The flavonoid-metal complexes showed obviously stronger bioactivities such as antibiosis, antivirus, anti-inflammatory, anti-tumor and anti-free-radical, possibly because of the stronger binding force caused by the change in complex structure and accessibility to target spots, or the synergy effect between flavonoids and metallic ions. This essay summarizes studies on bioactivity and mechanism of flavonoid-metal complexes, in order to provide reference for in-depth study and development on effective constituents contained in flavonoid traditional Chinese medicines. PMID:23019867

  6. Effect of hydrothermal processing on total polyphenolics and antioxidant potential of underutilized leafy vegetables, Boerhaavia diffusa and Portulaca oleracea

    PubMed Central

    Nagarani, Gunasekaran; Abirami, Arumugam; Nikitha, Prasad; Siddhuraju, Perumal

    2014-01-01

    Objective To investigate the effect of different processing methods on antioxidant properties of acetone extract of aerial parts from Boerhaavia diffusa and Portulaca oleracea. Methods The total phenolic and flavonoid contents were determined by Folin-Ciocalteau and aluminum chloride method, respectively. FRAP, metal chelating activity, DPPH, ABTS, nitric oxide, hydroxyl and superoxide radical scavenging activities, carotene/linoleic acid bleaching activity were used for the determination of antioxidant capacity. Results The total phenolics in Boerhaavia diffusa (82.79-162.80 mg GAE/g extract) were found to be higher when compared to that of Portulaca oleracea (22.94-10.02 mg GAE/g extract). Hydrothermal processing enhanced the level of inhibition on synthetic radicals such as DPPH (3 439-309 549 mmol TE/g extract) and ABTS (17 808-53 818 mmol TE/g extract) as well as biologically relevant radicals such as superoxide anion (70%-90%) and nitric oxide (49%-57%). In addition, boiling of the vegetables were found to be maximum capacity of FRAP (6 404.95 mmol Fe (II)/g extract) and metal chelating activity (1.53 mg EDTA/g extract) than the respective raw samples. Conclusions The present investigation suggests that the processing enhance the functionality and improves the availability of bioactive substances of these vegetables. In addition, they also exhibited more potent antioxidant activity. Therefore these natural weeds from the crop land ecosystem could be suggested as cost effective indigenous green vegetables for human diet and potential feed resources for animals. Further extensive studies on role and importance of those weeds in sustaining the agro biodiversity are also needed. PMID:25183131

  7. MHD Effects on Surface Stability and Turbulence in Liquid Metal

    NASA Astrophysics Data System (ADS)

    Bell, Lauren; Ji, Hantau; Zweben, Stewart

    2000-10-01

    Magnetohydrodynamic (MHD) turbulence is a significant element in understanding many phenomena observed in space and laboratory plasmas. MHD models also appropriately describe behaviors of liquid metals. Currently, there are many interests in the utilization of liquid metal in fusion devices; therefore an understanding of MHD physics in liquid metals is imperative. A small experiment has been built to study the MHD effects on turbulence and surface waves in liquid metal. To fully examine the MHD properties, a reference case in hydrodynamics is established using water or Gallium without the presence of the magnetic field or electrical current. An external wave driver with varying frequency and amplitude excites surface waves on the liquid metal. The experimental case using Gallium is run with the presence of the magnetic field and/ or electric pulses. The magnetic field is induced using two magnetic field coils on either side of the liquid metal and the electrical current is induced using electrodes. The measured dispersion relations of the two cases are then compared to the theoretical predictions. Several diagnostics are used in concert to accurately measure the wave characteristics. The surface waves will be recorded visually through a camera and the amplitude and frequency of the waves will be measured using a laser and fiber-optic system. This successful experiment will significantly enhance knowledge of liquid metal wave behavior and therefore aid in the applications of MHD in fusion plasmas. This worked was conducted as part of the DOE-sponsored National Undergraduate Fellowship Program in Plasma Physics

  8. About some measurements done on Honduras during the total solar eclipse of 11 July 1991

    NASA Astrophysics Data System (ADS)

    Pineda de Carías, María Cristina

    1995-01-01

    A morphological description of the solar photosphere, chromosphere and the corona is presented from a complete sequence of visual and spectroscopic observations made in Honduras (Amapala), during the total solar eclipse of 11 July 1991 and from the analysis of some emission and absorption lines at all the eclipse phases. Also, a comparison of detected total flux of muons incident over Tegucigalpa (Honduras) the day of the solar eclipse with data obtained years before is presented along with an analysis of the measurements of the total geomagnetic field done in Amapala (Honduras), before and on 11 July, in order to detect any change associated to the event of the solar eclipse.

  9. Lubrication and friction prediction in metal-on-metal hip implants

    NASA Astrophysics Data System (ADS)

    Wang, F. C.; Brockett, C.; Williams, S.; Udofia, I.; Fisher, J.; Jin, Z. M.

    2008-03-01

    A general methodology of mixed lubrication analysis and friction prediction for a conforming spherical bearing in hip implants was developed, with particular reference to a typical metal-on-metal hip replacement. Experimental measurement of frictional torque for a similar implant was carried out to validate the theoretical prediction. A ball-in-socket configuration was adopted to represent the articulation between the femoral head and the acetabular cup under cyclic operating conditions of representative load and motion. The mixed lubrication model presented in this study was first applied to identify the contact characteristics on the bearing surfaces, consisting of both fluid-film and boundary lubricated regions. The boundary lubricated contact was assumed to occur when the predicted fluid film thickness was less than a typical boundary protein layer absorbed on the bearing surfaces. Subsequently, the friction was predicted from the fluid-film lubricated region with viscous shearing due to both Couette and Poiseuille flows and the boundary protein layer contact region with a constant coefficient of friction. The predicted frictional torque of the typical metal-on-metal hip joint implant was compared with the experimental measurement conducted in a functional hip simulator and a reasonably good agreement was found. The mixed lubrication regime was found to be dominant for the conditions considered. Although the percentage of the boundary lubricated region was quite small, the corresponding contribution to friction was quite large and the resultant friction factor was quite high.

  10. 6. DOUBLE METAL DOORS ON WEST SIDE WITH CABLES ENTERING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. DOUBLE METAL DOORS ON WEST SIDE WITH CABLES ENTERING GROUND AT NORTH END OF BUILDING. - Chollas Heights Naval Radio Transmitting Facility, Helix House, 6410 Zero Road, San Diego, San Diego County, CA

  11. View of building 11050, showing metal clad addition on east ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View of building 11050, showing metal clad addition on east elevation, looking southwest. - Naval Ordnance Test Station Inyokern, China Lake Pilot Plant, Machine Shop, C Street, China Lake, Kern County, CA

  12. 41. Detail of punch press on left and large metal ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    41. Detail of punch press on left and large metal plate shear, Boiler Shop, located in north end of Machine Shop Building. - Thames Tow Boat Company, Foot of Farnsworth Street, New London, New London County, CT

  13. Electrocatalytic reduction of carbon dioxide on post-transition metal and metal oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    White, James L.

    The electroreduction of carbon dioxide to liquid products is an important component in the utilization of CO2 and in the high-density storage of intermittent renewable energy in the form of chemical bonds. Materials based on indium and tin, which yield predominantly formic acid, have been investigated in order to gain a greater understanding of the electrochemically active species and the mechanism of CO2 reduction on these heavy post-transition metals, since prior studies on the bulk metals did not provide thermodynamically sensible reaction pathways. Nanoparticles of the oxides and hydroxides of tin and indium have been prepared and characterized by transmission electron microscopy, X-ray diffractometry, X-ray photoelectron spectroscopy, and various electrochemical methods in order to obtain structural information and analyze the role of various surface species on the CO2 reduction pathway. On both indium and tin, metastable surface-bound hydroxides bound CO2 and formed metal carbonates, which can then be reduced electrochemically. The relevant oxidation state of tin was suggested to be SnII rather than SnIV, necessitating a pre reduction to generate the CO2-binding species. Metallic indium nanoparticles partially oxidized in air and became highly efficient CO2 reduction electrocatalysts. Unit Faradaic efficiencies for formate, much higher than on bulk indium, were achieved with only 300 mV of overpotential on these particles, which possessed an oxyhydroxide shell surrounding a conductive metallic core. Alloys and mixed-metal oxide and hydroxide particles of tin and indium have also been studied for their carbon dioxide electrocatalytic capabilities, especially in comparison to the pure metal species. Additionally, a solar-driven indium-based CO2 electrolyzer was developed to investigate the overall efficiency for intermittent energy storage. The three flow cells were powered by a commercial photovoltaic array and had a maximum conversion efficiency of incident

  14. On local total strain redistribution using a simplified cyclic inelastic analysis based on an elastic solution

    NASA Technical Reports Server (NTRS)

    Hwang, S. Y.; Kaufman, A.

    1985-01-01

    Strain redistribution corrections were developed for a simplified inelastic analysis procedure to economically calculate material cyclic response at the critical location of a structure for life prediction purposes. The method was based on the assumption that the plastic region in the structure is local and the total strain history required for input can be defined from elastic finite element analyses. Cyclic stress-strain behavior was represented by a bilinear kinematic hardening model. The simplified procedure has been found to predict stress-strain response with reasonable accuracy for thermally cycled problems but needs improvement for mechanically load cycled problems. This study derived and incorporated Neuber type corrections in the simplified procedure to account for local total strain redistribution under cyclic mechanical loading. The corrected simplified method was exercised on a mechanically load cycled benchmark notched plate problem. Excellent agreement was found between the predicted material response and nonlinear finite element solutions for the problem. The simplified analysis computer program used 0.3 percent of the CPU time required for a nonlinear finite element analysis.

  15. A Total Ozone Dependent Ozone Profile Climatology Based on Ozone-Sondes and Aura MLS Data

    NASA Astrophysics Data System (ADS)

    Labow, G. J.; McPeters, R. D.; Ziemke, J. R.

    2014-12-01

    A new total ozone-based ozone profile climatology has been created for use in satellite and/or ground based ozone retrievals. This climatology was formed by combining data from the Microwave Limb Sounder (MLS) with data from balloon sondes and binned by zone and total ozone. Because profile shape varies with total column ozone, this climatology better captures the ozone variations than the previously used seasonal climatologies, especially near the tropopause. This is significantly different than ozone climatologies used in the past as there is no time component. The MLS instrument on Aura has excellent latitude coverage and measures ozone profiles daily from the upper troposphere to the lower mesosphere at ~3.5 km resolution. Almost a million individual MLS ozone measurements are merged with data from over 55,000 ozonesondes which are then binned as a function of total ozone. The climatology consists of average ozone profiles as a function of total ozone for six 30 degree latitude bands covering altitudes from 0-75 km (in Z* pressure altitude coordinates). This new climatology better represents the profile shape as a function of total ozone than previous climatologies and shows some remarkable and somewhat unexpected correlations between total ozone and ozone in the lower altitudes, particularly in the lower and middle troposphere. These data can also be used to infer biases and errors in either the MLS retrievals or ozone sondes.

  16. Determining toxicity of lead and zinc runoff in soils: salinity effects on metal partitioning and on phytotoxicity.

    PubMed

    Stevens, Daryl P; McLaughlin, Mike J; Heinrich, Tundi

    2003-12-01

    When assessing cationic metal toxicity in soils, metals are often added to soil as the chloride, nitrate, or sulfate salts. In many studies, the effects of these anions are ignored or discounted; rarely are appropriate controls included. This study used five soils varying in pH, clay content, and organic matter to determine whether salinity from counter-ions contributed to or confounded metal phytotoxicity. Varying rates of Pb and Zn were applied to soils with or without a leaching treatment to remove the metal counter-ion (NO3-). Lactuca sativa (lettuce) plants were grown in metal-treated soils, and plant dry weights were used to determine median effective concentrations where there was a 50% reduction in yield (EC50s) on the basis of total metals measured in the soil after harvest. In two of the five soils, leaching increased the EC50s significantly for Zn by 1.4- to 3.7-fold. In three of the five soils, leaching increased the EC50s significantly for Pb by 1.6- to 3.0-fold. The shift in EC50s was not a direct result of toxicity of the nitrate ion but was an indirect effect of the salinity increasing metal concentrations in soil solution and increasing its bioavailability for a given total metal concentration. In addition, calculation of potential salinity changes in toxicological studies from the addition of metals exhibiting strong sorption to soil suggested that if the anion associated with the metal is not leached from the soil, direct salinity responses could also lead to significant overestimation of the EC50 for those metals. These findings question the relevance of the application of single-metal salts to soils as a method of assessing metal phytotoxicity when, in many cases in our environment, Zn and Pb accumulate in soil over a period of time and the associated counter-ions are commonly removed from the soil during the accumulation process (e.g.. roof and galvanized tower runoff). PMID:14713044

  17. Some heavy metals in soils treated with sewage sludge, their effects on yield, and their uptake by plants

    SciTech Connect

    Valdares, J.M.A.S.; Gal, M.; Mingelgrin, U.; Page, A.L.

    1983-01-01

    The possible use of sludge with high heavy metal concentrations and at high rates in calcareous soil was demonstrated in this study. Mixtures of two sludges were added to soils in various proportions up to 4% sludge content. One sludge was rich in Ni and Cd, while the other was relatively poor in heavy metals. Three soils varying in pH from 7.7 to 5.5 were tested. The concentrations of Cd, Ni, Cu and Zn in the DTPA and saturation extracts of the soil-sludge mixtures were determined and correlated with their uptake by plants and the yield of Swiss chard (Beta vulgaris L., cv. Ford Hook Giant) grown on these mixtures. The metal-poor sludge hardly affected the yield of the relatively salt-resistant Swiss chard. The metal-rich sludge reduced the yield drastically in noncalcareous soils after a critical amount of that sludge (1.5%) was added to the soils. Yet, even 4% of this metal-rich sludge increased the yield of Swiss chard, as compared with the sludge-free control in a calcareous soil. The best fit to yield was obtained by multiple regression with metal content in the soil saturation extract. The solubility in soil solution of Cd, Ni and Zn was strongly affected by the pH. The uptake of Ni and Zn by plants was significantly larger in the acid soil than in the calcareous soil. The difference in the uptake of Cd and Cu between the soils was smaller. Plant uptake of the metals was generally predicted better by the total metal addition or concentration in the DPTA extract than by metal concentration in the soil saturation extract. In noncalcaeous soils the total metal addition correlated as well as metal content in the DTPA extracts with the metal concentration in the soil solution, with the uptake by plants and with the yield.

  18. Laminate articles on biaxially textured metal substrates

    DOEpatents

    Beach, David B.; Morrell, Jonathan S.; Paranthaman, Mariappan; Chirayil, Thomas; Specht, Eliot D.; Goyal, Amit

    2003-12-16

    A laminate article comprises a substrate and a biaxially textured (RE.sup.1.sub.x RE.sup.2.sub.(1-x)).sub.2 O.sub.3 buffer layer over the substrate, wherein 0metal-organic decomposition. The laminate article can include a layer of YBCO over the (RE.sup.1.sub.x RE.sup.2.sub.(1-x)).sub.2 O.sub.3 buffer layer. A layer of CeO.sub.2 between the YBCO layer and the (RE.sup.1.sub.x RE.sup.2.sub.(1-x)).sub.2 O.sub.3 buffer can also be include. Further included can be a layer of YSZ between the CeO.sub.2 layer and the (R.sup.1.sub.x RE.sup.2.sub.(1-x)).sub.2 O.sub.3 buffer layer. The substrate can be a biaxially textured metal, such as nickel. A method of forming the laminate article is also disclosed.

  19. Effect of femoral head size on risk of revision for dislocation after total hip arthroplasty

    PubMed Central

    Kostensalo, Inari; Junnila, Mika; Virolainen, Petri; Remes, Ville; Matilainen, Markus; Vahlberg, Tero; Pulkkinen, Pekka; Eskelinen, Antti; Mäkelä, Keijo T

    2013-01-01

    Background and purpose Previous population-based registry studies have shown that larger femoral head size is associated with reduced risk of revision for dislocation. However, the previous data have not included large numbers of hip resurfacing arthroplasties or large metal-on-metal (> 36-mm) femoral head arthroplasties. We evaluated the association between femoral component head size and the risk of revision for dislocation after THA by using Finnish Arthroplasty Register data. Patients and methods 42,379 patients who were operated during 1996–2010 fulfilled our criteria. 18 different cup/stem combinations were included. The head-size groups studied (numbers of cases) were 28 mm (23,800), 32 mm (4,815), 36 mm (3,320), and > 36 mm (10,444). Other risk factors studied were sex, age group (18–49 years, 50–59 years, 60–69 years, 70–79 years, and > 80 years), and time period of operation (1996–2000, 2001–2005, 2006–2010). Results The adjusted risk ratio in the Cox model for a revision operation due to dislocation was 0.40 (95% CI: 0.26–0.62) for 32-mm head size, 0.41 (0.24–0.70) for 36-mm head size, and 0.09 (0.05–0.17) for > 36-mm head size compared to implants with a head size of 28 mm. Interpretation Larger femoral heads clearly reduce the risk of dislocation. The difference in using heads of > 36 mm as opposed to 28-mm heads for the overall revision rate at 10 years follow-up is about 2%. Thus, although attractive from a mechanical point of view, based on recent less favorable clinical outcome data on these large heads, consisting mainly of metal-on-metal prostheses, one should be cautious using these implants. PMID:23799348

  20. Hybrid alumina total hip arthroplasty using a press-fit metal-backed socket in patients younger than 55 years. A six- to 11-year evaluation.

    PubMed

    Bizot, P; Hannouche, D; Nizard, R; Witvoet, J; Sedel, L

    2004-03-01

    Between 1990 and 1992, we implanted 71 hybrid alumina-on-alumina hip arthroplasties in 62 consecutive patients under the age of 55 years, with a mean age of 46 years at surgery. There were 56 primary and 15 secondary procedures. The prostheses involved a cemented titanium alloy stem, a 32 mm alumina head, and a press-fit metal-backed socket with an alumina insert. Three patients (four hips) died from unrelated causes. Four hips had revision surgery for either deep infection, unexplained persistent pain, fracture of the alumina head, or aseptic loosening of the socket. The nine-year survival rate was 93.7% with revision for any cause as the end-point and 98.4% with revision for aseptic loosening as the end-point. The outcome in the surviving patients (50 patients, 57 hips) with a minimum five-year follow-up (mean eight years) was excellent in 47 hips (82.5%), very good in eight (14%), good in one and fair in one. A thin, partial, lucent line, mainly in zone III was present in 38% of the sockets and one socket had a complete lucency less than 1 mm thick. One stem had isolated femoral osteolysis. There was no detectable component migration nor acetabular osteolysis. This hybrid arthroplasty gave satisfactory medium-term results in active patients. The press-fit metal-backed socket appeared to have reliable fixation in alumina-on-alumina hip arthroplasty. The excellent results using cemented fixation of the stem may be related to the low production of wear debris. PMID:15046431